Breeding corydoras catfish
What you will need
24 inch aquarium with hood and light
- soft sandy substrate
- stones,coconut shells,flowerpots and tree roots
- densely planted rear of the aquarium
- floating plants
- breeding group of 5 adults or more
- sponge filter with airpump
- 100w heater – stat
Generally keep corys at a temperature of75F, water acidity at ph 7, and hardness at 6dh. They make excellent community fish but need to be kept as a group because they get lonely.
Breeding set up
Set up the breeding aquarium with water from the main aquarium and transfer a sponge filter to the aquarium. Set up the aquarium with plants (including floating plants) and hiding places such as pots and coconut shells. When your corys look healthy and the female looks plump then it is time to choose your breeding group and move them to the prepared breeding tank.
Put around 5 healthy adult specimens in the breeding tank. Include only 1 or 2 males. Then condition them with live food for a week. The water in the breeding tank should only be 8 inches high. There should only be a thin layer of sand on the floor. Simulate a long day by leaving the light on from morning until night, at least 12 hours. After that lower the temperature by 2 degrees per day. Continue until the temperature reaches 68F.
This should trigger spawning. Mating is unusual with 2 or 3 males following the female. One male will present his pelvic area for the female to attach to. This is quite a manic affair. They pull each other through the tank. The female presses her mouth tightly against the male’s pelvic area. They form a T-shape. He releases sperm which passes through to her eggs which are held in her cupped pelvic fins and they become fertilised. Other males try to push themselves into the same T-position, but it is usually the stronger males that succeed.
The female will then frantically wander around the aquarium in search of a spawning site. She will in a single motion, clean an area of plant, the aquarium glass or a stone and quickly she lay a batch of eggs there. This is so quick you might miss it. Then the T-position will restart. This repeats several times until her egg supply is finished. She may lay about 200 eggs. In between batches the parents may graze on the eggs. Remove the fish immediately after spawning has finished to maximise the number of eggs surviving. Corys get very hungry after mating.
Raising the fry
Add some methylene blue to the water. Start raising the temperature again by 2 degrees per day until it reaches 74F. The eggs hatch after 5 days and become free swimming 2 days later. The fry look like typewriter commas and stay on the ground. Start feeding brineshrimp and microworms. After another week start feeding them crushed fish food. At one month old they should be 0.5 inch long. At 2.5 months they should be 1 inch in length and sellable.
Corydoras are also known as cory catfish. They are freshwater fish that is extremely popular with aquarium enthusiasts all over the world. What is especially appealing about these fish is that they are very social and like to be kept in groups of 6-7 or more of their own species as well as other breeds of fish. These types of fish groups are called schools.
If you have a tank full of corydoras, count yourself very lucky! You will be able to introduce other similar temperamental fish to the aquarium without getting any trouble from your cory catfish. In fact, if you have tetras or other similar colored fish in the tank, the cory catfish will swim with them playfully.
Another benefit of having a school of cory catfish in your aquarium is that they will help keep your tank clean. Corydoras are bottom feeders. This means that they spend most of their lives at the bottom of the tank, looking for leftover food and other debris to nibble on. Bottom feeders, in general, are great tank companions for messy fish and make your life that much easier when it comes to cleaning the tank.
Read Related Article: Glow Fish Breeding
Corydoras is the scientific name for cory catfish. We will be referring to them by both names throughout this article, so don’t get confused. Most fish have a scientific name as well as a ‘street’ name, in this case, the scientific name and street name are just as commonly used.
Corydoras Fun Facts
- Female corydoras are a little larger than males. They can grow up to 3 inches long, while the males reach roughly 2.5 inches.
- Adult cory catfish don’t have teeth. You may notice small teeth-like ridges on larvae and young cory catfish. They soon lose those baby teeth and are left as gummy adults.
- Cory catfish live for a maximum of 5 years. They will only reach this age if you keep them happy and healthy. Do not forget that the happiness of your fish is just as important as their health.
- Corydoras can’t get pregnant. They are egg-laying fish, so they do not give birth to live larvae.
- Corydoras aren’t fussy when it comes to their food, they will eat both plants and meat.
- They love to eat, but make sure their meal sinks to the bottom of the tank. Cory catfish are a little lazy and would rather their meal comes to them.
- There are 161 recognized species of corydoras.
- Corydoras like to eat zucchini and squash every now and then.
- Corydoras can breathe atmospheric oxygen through their posterior intestine and will often surface to take a breath of air.
Where Are Corydoras Found in the Wild?
You won’t find these fish in the sea, instead, they are in ponds, streams, rivers, and marshes. They prefer a slow-moving flow of water. Cory catfish are native to South America. The most important thing for corydoras is to be situated in shallow and murky water.
Corydoras were discovered between 1831-1836 by none other than Charles Darwin. Charles Darwin stumbled across these little fish on his 5-year famous voyage on the Beagle. Good job Charles!
What Makes Corydoras So Special?
These fish are so popular because of their laid-back, easy-going nature. They don’t ask for too much and won’t cause a fuss among other fish species. Cory catfish even befriend other fish species.
As we mentioned earlier, they love to feed on other fish’s leftover food, from the substrate, assisting in keeping their environment clean. Bottom-dwelling fish are really important when you have a sand or gravel substrate in your tank. This is because they are constantly moving the substrate around, filtering the water as they go about their business.
Tanks that do not have a bottom-dwelling fish will need to be cleaned and looked after a little more frequently, especially if there is a sand substrate in the tank. Sand will discolor very quickly and dangerous gas pockets form in the sand if it isn’t looked after by a bottom dweller. Raking the sand with your hand now and then will help slow this process down.
Read Related Article: Axolotl Breeding
Corydoras And Egg Laying
Corydoras, like many other spawning fish, have a tendency to eat their own eggs. Therefore, it is important to separate the cory catfish from the eggs as soon as the eggs have been laid and the spawning session is over. The most important part of looking after the eggs is actually ensuring the adult fish are out of the tank ASAP to prevent the corydoras from eating their fry.
Corydoras eat their own fish in the wild too. This is their way of controlling their population. We are unsure if corydoras eat eggs that they think are genetically impaired or if they just do it as a survival instinct.
The fry tank and the breeding tank can be the same. Although corydoras can spawn in their regular community tank, it is best to move them so that you don’t have to handle the eggs.
Make sure that the breeding/fry tank is fully cycled before prompting your fish to breed. This tank should be as simple as possible, no need for fancy accessories in your breeding tank as that just makes it that much harder to clean.
Corydoras eggs take just 3-5 days to hatch, hence the importance of having a breeding tank ready and cycled. If you are having trouble cycling your tank, use a good water conditioner and beneficial bacteria to speed up the process a little.
Cory catfish females will swim with their fertilized eggs to a flat surface for depositing. They like to place the eggs on something soft like moss.
When Are Corydoras Old Enough to Mate?
It is probably best to wait until your corydoras are 12 months old before breeding them. This ensures you do not waste your time attempting to breed fish that aren’t sexually mature yet.
The act of spawning can be extremely stressful for fish if they are not sexually mature. Another reason why breeding your fish prematurely is a bad idea. It is most likely that your male corydoras will be sexually mature between 6-9 months old, but try and refrain from breeding them this early on.
Make sure your corydoras are at least 2.5 inches long before breeding them, even if they are 12 months old. After all, fish mature at different rates, and size is the best indicator here.
If you are an inpatient breeder and want to get your corydoras population up as quickly as possible, you will be glad to know that they are extremely easy to breed. You may even get between 15-20 healthy fish from one spawning session. Brilliant!
Read Related Article: Breeding Corydoras
How Often Can You Breed Corydoras?
You can breed your corydoras whenever you like as long as you follow the following instructions for preparation.
- You obviously need to pick healthy fish. This may seem like a no-brainer, but sometimes the fish are not in the best condition for breeding. If you have had to medicate your fish for any reason I would suggest waiting a few more weeks before starting the breeding process to ensure healthy offspring.
- Next, you need to reassess where your breeding/fry tank is to be situated. If it is near a window you will need to bear in mind that natural light and outside temperatures will interfere with the breeding activities in the aquarium. Try and move the breeding tank to a quiet, dark area of the room so that you have control over the light. (13 hours of soft light per day is perfect)
- Place a little hiding spot in the tank. This can be something super simple like a large plant or a cave of some sort (broken coconut shells are great for corydoras).
- Ensure the tank conditions are optimal. The water PH level should be between 6 and 8, and the temperature between 75-78 degrees Fahrenheit. Ensure that you perform 50% daily water changes so that the water stays clean. The water should be pretreated before putting it in the tank with the fish to avoid ‘new tank syndrome’.
- Do not try and breed one corydoras couple at a time. As we mentioned earlier, they are extremely social and will not ‘get in the mood’ if there are just a couple of fish in the tank. Instead, have 3 or 4 females and the same amount of males together in the breeding tank and watch the magic happen.
You want to have a larger aquarium prepared, cycled, and ready for action when your new fry is ready to be populated should you find that your tank isn’t large enough for any more companions. You will have roughly 4 to 5 weeks from when the eggs are laid to when the fry are ready to be moved in with the rest of the family.
Please note that brand new tanks can take up to 8 weeks to cycle. It also isn’t a process that can be rushed. Most of the time, with the right tank conditioners, beneficial bacteria, and sufficient equipment it will be a little quicker. Nonetheless, prepare for the worst possible outcome and you won’t get any shocks or run into hurdles along the way.
For Your Information: New tank syndrome is when an aquarium has an immature or inadequate filter system. Beneficial bacteria are vital for the fish to ensure ammonia levels are kept low. Large water changes can remove the beneficial bacteria and cause the fish to get sick if the replacement water is too ‘fresh’.
Tank Conditions For Breeding Corydoras
Cory catfish need a tank that holds approximately 30 gallons of water, even though they are only little fish. Think of it this way, corydoras like to live in schools and can be kept with other fish species and plants. This requires a lot of tank space, thus having a tank big enough is key to keeping your fish in the best condition.
The tricky part about keeping a lot of little fish together in a tank is they like to swim around each other. Larger fish tend to be a little lazier than small fish, something that fishkeepers do not expect at first.
The tank may look big enough for your fish, but have a look at how they act in the tank. If they are constantly looking startled and as if they are trying to get away from one another, you should consider a bigger tank.
In the breeding tank you will need the following:
Corydoras are especially sensitive to temperature changes in the water. Having a reliable heater will ensure your breeding fish are happy. Eventually, when the eggs are laid and the fry hatch, the water temperature will be even more important.
Canister filters are a good choice, you can also go for a sponge filter if you prefer.
If you want to go all out and throw in a few live plants, LED lights are a must. Plus they do make the tank look much nicer. The lights will help you spot the eggs and fry if they are hiding in there.
Think of the tank’s substrate as your lovely cozy blanket. It’s super important to you, right? That is how the corydoras feel about sand. Anything other than sand will damage the fish and cause them discomfort. That certainly won’t get them to breed successfully.
Don’t overdo it on the vegetation in your breeding tank. Having a few well-trimmed plants in the aquarium will make the fry feel safer in their first few days. Java moss, crypts, and pennywoods are good plants to have in your breeding tank.
Identifying If Your Corydora Is Male Or Female
You can not possibly tell the difference between male and female corydoras when the fish are sexually immature. Well, not unless you are a cory catfish expert, of course.
Wait until the cories are a year old, or 2.5 inches long, and observe them in the aquarium. You will notice that some look a little thicker and chunkier in general. These are females. In comparison, the males are super slim and look like younger fish.
Do Corydoras Change Gender?
Corydoras do not change sex. If they are born male they will stay male for the rest of their lives, and the same goes for females. Any supposed gender changes are purely due to mistaken identity.
What To Do When Corydoras Lay Eggs
As soon as the corydoras have laid their eggs, take the adults out of the breeding tank and place them back into the population tank. You can either leave the eggs in the breeding tank and take care of them there or move the eggs into a fry tank.
Either method works brilliantly, however, less experienced cory catfish breeders should avoid handling the eggs altogether as they are very fragile. As long as the breeding tank is rather minimal and uncluttered, the fry will be very happy in the tank once the eggs hatch.
How To Look After Corydora Fry
Once your fry hatch, they won’t need to be fed for about 23-48 hours as they still feed off the remaining yolk sack in their stomachs. Once you notice the fry start to wriggle and giggle about more than usual, you will need to feed them twice per day.
Newborn fry will only require powder food in their first week of life. Once the fry has grown a little (after a week or so of dry food) you can introduce either live or dead protein. Baby brine shrimp are a delicacy for cory catfish. On their 3rd or 4th week of life, you should start to feed them frozen daphnia.
You may notice a fry or two are not quite as strong as the rest, or maybe they are slightly deformed. If you are breeding your fish for your pleasure then leaving weaker fish with genetic issues is fine. If you want strong fish that will be suitable to breed in the future then this weaker fry should be separated from the rest.
When your fry is large enough to move into the general population tank, make sure the tank is big enough to house all of the fish. If you do not have a large enough tank and do not wish to have a bigger tank, give some fish away.
So there you have it. Your complete breeding guide for the cory catfish. You can follow these tips for all the cory catfish species. We hope you have found this information helpful. Happy breeding!
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Before you can attempt to breed your corydoras catfish, there are a few basics you need to know.
The first thing you need to know about breeding is that they are egg layers and they do not give birth to live young. Corydoras eggs are very sticky so the adults typically deposit them directly on the tank glass or on other tank surfaces such as the heater, filter, or even broad plant leaves.
A single spawning can produce anywhere between 20 and 400 eggs, dependant on factors such as the species of corydoras, and environment (temperature, water pH level and size of the breeding tank). Do note that it is unlikely for all of the eggs to be fertile in a single spawning.
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Sexing corydoras catfish can be somewhat challenging because you need to view the fish from above. When viewed from above, the female may appear broader and larger than the male while the male will have more pointed pectoral fins.
How to breed corydoras?
These fish tend to breed most readily in groups where the ratio of male-to-female fish is approximately 4 to 2. It is difficult to sex these fish, and so it is best to keep them in large groups to encourage natural pairing and spawning.
When the fish are ready to mate, the male will initiate the courting ritual by chasing the females around the aquarium. When the male finds the females, he can be seen lying on top of her until she is ready to release her eggs. When she is ready, the male moves next to her and releases his milt which the female collects in her mouth and uses to fertilize the eggs as she deposits them in small groups on various tank surfaces.
The entire spawning process typically takes about an hour and the female may take short breaks between each grouping of eggs.
How long does it take for corydoras eggs to hatch?
Once the eggs have been deposited, they will hatch after 4 to 6 days. It is important to note that corydoras and other fish are likely to eat the eggs so it is a good idea to either remove the adult fish from the tank or to transfer the eggs to a fry tank.
Your best bet is to spawn your corydoras catfish in a separate breeding tank so you can easily remove the adults from the tank after they spawn. This will give you the best chance of raising a large number of the fry to maturity after hatching.
Setting up a Breeding Tank
The key to ensuring that most of your corydoras catfish eggs hatch and develop is to spawn your fish in a breeding tank. That way you can remove the adults after spawning so they do not eat the eggs. This tends to be most common in community tanks, whereby those corydoras that are not breeding will more than likely eat the newly laid eggs of the breeding corydoras.
Setting up a breeding tank for corydoras catfish is not difficult, but there are a few parameters you should follow.
Below you will find a list of tips for setting up a breeding tank:
- Select a tank about 20 gallons (75 US Liters/90 UK Litres) in capacity, ideally with high sides.
- Leave the bottom of the breeding tank bare and decorate sparingly with large rocks and broad-leafed plants.
- Install a hang-on aquarium heater to maintain a temperature between 70°F and 75°F (21°C to 24°C).
- Add an air stone and an air pump to facilitate water flow. Do not use a hang-on filter because it could suck up and damage the eggs.
- Fill the tank to about 50% capacity with de-chlorinated water — match the water chemistry to the main tank, if possible.
- Some breeders add Indian Almond Leaves (Catappa Leaves), or dried cones from the alder tree (can be used with the same result) to their breeding tanks. This is done to avoid fungus infesting the eggs. Using a ramshorn snail can also help to prevent the fungus from infesting the eggs, as it will eat the fungus but not the eggs.
Once you have set up the breeding tank you should take the time to condition your fish for breeding. If possible, you may want to separate the sexes for a few weeks before spawning to ensure that they are eager to mate when you put them back together.
To condition your fish, keep the tank at a stable temperature between 70°F and 75°F (21°C to 24°C). Feed the fish a nutritious and varied diet of live, frozen, and pellet foods, offering small amounts of food 3 to 4 times per day.
After a month or so of conditioning, it should be easier to tell the two sexes apart (if you have not separated them already) so you can create the recommended ratio for breeding purposes.
Raising the Newly Hatched Fry
After conditioning your corydoras, the next stage is to place them in the breeding tank and let them do the rest. If you find that your corydoras do not automatically engage in breeding behavior after adding them to the breeding tank, there are a few things you can do to encourage them.
Maintain the tank temperature between 70°F and 75°F (21°C to 24°C) for a few days and continue to feed the fish a nutritious and varied diet.
After three or four days in the breeding tank, add cool water to the tank at night to facilitate a 2 to 4 drop in temperature.
After a few days, the temperature in the tank should have dropped to about 65°F (18°C). This drop in temperature is designed to simulate the rainy season in the corydoras natural environment which is the period during which they typically breed.
If this does not work, siphon out 50% of the tank water and try again. As long as you have properly conditioned the fish, they should breed readily within a few days.
As mentioned previously, corydoras catfish are capable of producing anywhere between 20 and 400 eggs in a single spawning and it generally takes 4 to 6 days for the eggs to hatch.
What do corydoras fry eat?
When they first hatch, the fry will be very small so you will need to feed them very small amounts of food.
Newly hatched brine shrimp are the ideal food for corydoras fry. Feed them small amounts several times a day for the first week until they grow large enough to handle other foods.
Once the fry are large enough you can transition them onto daphnia, micro-worms, and finely crushed flake food.
After a week you should also begin to perform daily water changes of about 5% of the tank volume. In addition to these water changes, you may also want to add a sponge filter to the breeding tank. This will help to control accumulated debris and will also encourage healthy biological filtration in your breeding tank.
By the time the fly are 3 to 4 weeks old, they should be large enough to accept regular foods and you will also be able to add a regular hang-on or canister filter to your tank without having to worry about injuring the fry.
Hi, my name is Sean, and I’m the primary writer on the site. I’m blogging mostly about freshwater and saltwater aquariums, fish, invertebrates, and plants. I’m experienced in the fishkeeping hobby for many years. Over the years I have kept many tanks, and have recently begun getting more serious in wanting to become a professional aquarist. All my knowledge comes from experience and reading forums and a lot of informative sites. In pursuit of becoming a professional, I also want to inspire as many people as I can to pick up this hobby and keep the public interest growing.
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Cory Catfish (also known as Corydoras, Cory Cats, and Armored Catfish) are one of the most popular species in freshwater fish-keeping.
They are loved by aquarists of all skill levels for their mild temperament, gentle nature, and unique characteristics.
In this complete guide, we break down everything you need to know about keeping, breeding, and caring for Cory Catfish.
If you are looking for a specific section, use the quick links below to skip around the page for quicker reading. Lets dive in!
|Common Name||Cory Catfish|
|Color||Variety of Natural Shades|
|Suggested Tank Size||20 gallons|
|Water Temperature Requirements||70° – 80°F|
|pH Requirements||6.0 – 8.0|
|Temperament & Compatibility||Very Peaceful|
About Cory Catfish
- Scientific Name: Corydoras
- Temperament: Peaceful
- Care Level: Easy
- Origin: South America
- Common Names: Cory Catfish, Corydoras, Cory Cats, Armored Catfish
When it comes to temperament, Cory Catfish are one of the most desirable fish in the hobby. Their peaceful and calm demeanor is almost endearing.
In addition, Corydoras get along with just about every species – that said, they are very non-aggressive and usually won’t “stick up for themselves”, so don’t keep them with aggressive tank mates.
Don’t assume that Corydoras’ well-mannered behavior means that they’re boring, though. Cory Catfish are active and entertaining to watch at all hours of the day.
They are an extremely social fish and should be kept in groups of 5 or more – trust me, watching your Corydoras interact with each other is unlike any other fish in the hobby.
Cory Catfish originate from small streams and lakes in South America.
Their natural habitat is rich with live plants and other hiding places, so try to recreate that as best as possible.
Another important note about the natural habitat of Cory Catfish is they they are much more comfortable with sand substrates than gravel/rocky substrates.
Gravels and other rough substrates are not recommended because they have the tendency to damage Corydoras’ barbels and fins.
A lot of references claim that Corydoras live between 5-7 years. While this might be true in the wild, Cory Catfish can actually live much longer in captivity.
In the right conditions, Cory catfish are know to live between 12-15 years. There are even some documented cases of aquarium owners keeping Corys for 20+ years!
Corydoras are pretty small for catfish standards. In general, Cory Catfish size usually ranges from 1.5 to 2.5 inches (4-7 cm) depending of the species.
That said, breeding females can reach 3+ inches in older age.
Cory Catfish Care
Here are a few things you should know before attempting to keep Cory Catfish:
Tank Setup Requirements
Cory Catfish are generally pretty easy to care for. They don’t require large tank (much smaller that most other species of catfish) and are pretty forgiving when it comes to water condition.
Cory Catfish also get along great with other species – this combination makes them great for beginner fish-keepers.
- Tank Size: Cory Catfish are pretty small fish. Technically, a single Cory should be fine in a ten gallon tank. The problem is that Corydoras are not happy when kept by themselves. Since they are schooling fish, Cory catfish should be kept in groups of 5 or more. For a school of 5 Corys, a minumim tank size of 20 gallons is recommended.
- Water Flow: Cory Catfish love water flow and are often found “dancing” in areas with high flow. That said, try to have a few spots in your tank with low water flow so your Corys can rest (rock, slate and plants are a great way to do this).
Wild caught Cory catfish are know to be pretty picky when it comes to water condition – over the years, though, selective breeding has “toughened” tank bred Cory catfish into an extremely resilient and hardy species.
While I wouldn’t describe Corydoras as “difficult” to keep, every effort should be made to provide a pristine environment.
Here are some basic guidelines for water parameters when keeping these fish:
- pH: 6.0-8.0
- Temperature: 70-80°F
- Alkalinity: 3°-10° dKH
When caring for Cory catfish, stability is much more important than hitting that perfect pH and temperature.
If you’re parameters are a few degrees off, don’t worry about it too much – DO try to keep it as stable as possible.
Cory catfish are also especially sensitive to ammonia, nitrite, and nitrate. The first two are the most important – ammonia and nitrite can kill in no time.
This should go without saying, but make sure your tank is properly cycled before introducing any fish to your tank, let alone Corydoras.
Nitrate is a little more sneaky, though. It builds up in the water over time, even in perfectly healthy aquariums. Keep up with bi-weekly water changes to help bring nitrate levels down to safe levels.
The API Freshwater Master Test Kit is the best kit on the market for testing your aquarium water.
Cory Catfish Diet
Typical of any bottom feeder, Corydoras are amazing scavengers. In community tanks, they often find the majority of their food scouring the tank bottom.
That said, Cory catfish owners should never assume that their fish get enough food simply from leftover scraps.
Since Corydoras are omnivorous, they should be fed a balanced diet of plants-based and meat-based foods.
Personally, I have found Hikari Algae Wafers to be a Cory favorite (most flake foods are also sufficient). For the occasional meaty snack, Omega One Bloodworms are a great choice.
Since Corydoras are a little sensitive to changes in ammonia, nitrite, and nitrate, make sure you don’t overfeed. Only feed your fish as much as they can eat in a few minutes and remove anything they don’t seem to like.
Schooling Tendencies of Corydoras
We touched on this a little before, but it is very important that you keep Cory catfish in schools of 4 or more fish (5+ is preferable).
Corys are very social fish and can often be found “playing” and swimming in sync with others of their species. Their schooling antics are not only interesting and amazing to watch, but actually help make your catfish happier and healthier.
Cory Catfish Types – Common Species
There are over 170 different species of Corydoras Catfish, many of which haven’t even been named yet. When choosing a species for your tank, there are tons of different options.
Here are a few of our favorite Corydora species:
Panda Corys are one of the most popular species of Cory catfish, so they’re readily available at most local fish stores.
They are characterized by a cream-white body with dark black spots on their head and tail. Panda Corydoras grow to about 2″, though breeding-age females may get a little bit larger.
- Scientific Name: Corydoras panda
- Size: 2″
- pH: 6.0-7.0
- Temperature: 70-78°F
Albino Cory Catfish aren’t technically their own species – they are a selective-bred variation of the Bronze Cory. That said, Albino Corys are unique in more than a few ways.
Their golden-white bodies and light pink eyes create great contrast against plants and dark substrates, making them a popular pick among cory-lovers. In addition, Albino Corys are known for their “spazzy” personalities, which many aquarium owners find endearing.
- Scientific Name: Corydoras aeneus
- Size: 2.5″
- pH: 6.0-7.0
- Temperature: 72-80°F
As one of the most popular species of Corydoras, Peppered Corys can be found at most fish stores and online fish retailers.
Their coloration is generally tan with dark green and black patterns (and often a green “shine”). That said, no two Peppered Corys are the same – a trait that a lot of aquarium owners love.
- Scientific Name: Corydoras paleatus
- Size: 2.5-3″
- pH: 6.0-7.0
- Temperature: 72-80°F
Bronze Corys (a color variation of Green Corys) are known for being active, expressive, and easy to keep – even when compared to other Corydoras species.
They generally grow to about 2.5 inches (6.35 cm), though breeding females can grow to over 3 inches.
Though the coloration of Bronze Corys may not be as attractive as the other species on our list, they are a great choice for aquarists looking to learn about keeping and breeding Cory Catfish.
- Scientific Name: Corydoras aeneus
- Size: 2.5″
- pH: 6.0-7.0
- Temperature: 72-80°F
One of the rarer species of Corydoras on our list, Julii Corys are admired for their unique striped patterns.
Since true Julii Corys are generally hard to find, False Julii Corys (Corydoras trilineatus) are a great, more prevalent option for those who really love the striped pattern.
Like most other Cory species, Corydoras julii and Corydoras trilineatus are easy to care for and thrive in a range of water conditions.
- Scientific Name: Corydoras julii
- Size: 2.5″
- pH: 6.5-8.0
- Temperature: 72-80°F
One of the most visually appealing species of Corydoras, Sterbai Corys are a favorite among freshwater fish-keepers.
They are known for their energetic, comical personalities and are very tolerant of different water conditions. Like most Corys, Sterbai grow to about 2.5 inches.
- Scientific Name: Corydoras sterbai
- Size: 2.5″
- pH: 6.0-7.5
- Temperature: 73-82°F
Pygmy Corys are definitely the most unique species of Cory catfish on our list. Topping out at around 1″, this species is capable of living in smaller aquarium than other types of Corys.
Unlike other Cory species, Pygmy Corys don’t spend all their time on the tank bottom – in fact, they prefer to swim about mid-tank.
- Scientific Name: Corydoras pygmaeus
- Size: 1″
- pH: 6.4-7.4
- Temperature: 72-80°F
Cory Catfish Tank Mates
Although Corydora species-only tanks can be incredible, most aquarium owners like a little variety. Luckily, Cory catfish are compatible with (pretty much) anything that won’t try to eat them.
Here are a few great Corydoras tank mates for those looking to put together a community tank:
Suitable Tankmates for Cory Catfish
- Fancy Guppies
- Neon Tetras
Tankmates to Avoid
Here are a few species you definitely should not keep with Cory catfish:
- Cichlids: Cichlids in general tend to be too aggressive for Cories. Large species such as Oscars will outright eat them.
- Barbs: While Barbs aren’t overly aggressive, they are very nippy. Barbs often take advantage of the peaceful nature of Corydoras, causing stress and heavy competition for food.
Setting up a Cory Catfish Tank
If you’re looking to set up a Corydoras species-only tank, this is the section for you. We will go through everything you need to set up a gorgeous, natural Cory tank the right way.
- Tank: While a lot of resources will tell you that Cory catfish are fine in 10 gallon tanks, I really disagree. I highly recommend going with a 20 or 30 gallon setup if you want to keep a healthy shoal of Corys.
- Filtration: If you want to go the extra mile, canister filters are a great way to step up your filtration. If not, no worries – a hang on back filter should be just fine. I recommend the AquaClear Power Filter.
- Heater: A heater is a vital part of keeping your tank stable. I’ve use the Cobalt Aquatics Neotherm for years with great results.
- Lighting: If you are going to keep live plants (which Corys love), you are going to need an LED light. The NICREW Classic is a great low-cost option.
One of the most important pieces in any Cory catfish tank is the substrate. Unlike most freshwater fish, Corys DO NOT do well with gravel – the jagged edges can damage their fins and stomach.
Sand is, by far, the best option when it comes to keeping Cory Cats. I recommend CaribSea Super Naturals Sand (in the Sunset Gold color).
It is soft enough not to damage your Cory’s barbels and isn’t perfectly white, which helps the tank appear less dirty (white sand makes debris and algae much more visible).
If you don’t want to go with this sand, a lot of pool filter sands work great for Corys as well.
While sand it definitely your best option, it poses a problem with live plants. Sand has a low CEC (meaning it does not absorb nutrients well) – therefore, root tabs are necessary to supply your plants with the right nutrients.
Place them at the base of your plants underneath the substrate – within a few months, your sand should be mature enough that the root tabs will no longer be necessary
Adding Live Plants
Cory Cats are not picky at all when it comes to plants – in fact, just about any species should work. Here are a few beginner friendly aquarium plants that don’t require a ton of light or pristine water conditions:
- Anubias Nana
- Java Fern
- Java Moss
As we explained above, root tabs will be necessary for the first few months if you’re using any type of sand (especially for rooted plants). Once the tank matures, enough nutrients are absorbed into the substrate that the root tabs won’t be necessary.
In addition to plants, Cory Cats love hiding in driftwood and slate shelves. Feel free to get creative with your aquascaping and layout – this is the time for your creativity to shine!
Live plants require good lighting to thrive.
I really recommend going with an LED fixture for multiple reasons – they last longer, they put off much less heat, and produce healthier plants. As suggested above, the NICREW Classic is a good choice for those on a budget.
Although lighting is important for plants, Cory Catfish tend to enjoy low light environments. That said, Corys are very adaptable and will adjust to just about any light you throw at them.
Just try to make sure there are a few caves or similar structures present so that your Corys can escape the light once in a while.
This should go without saying, but make sure your tank is completely cycled before you introduce any fish. If you need any help with this process, read through our complete guide to the fishless cycle.
One of the best things about Cory Cat tanks (and planted tanks in general) is that it’s perfectly fine to add plants before cycling your aquarium. In fact, there is a lot of evidence that plants can actually help speed up the nitrogen cycle.
Use these few weeks to shop around for suitable plants, read about aquascaping, and getting your tank set up exactly how you want it.
Based on personal experience, giving your tank the proper time to cycle not only leads to a better laid out/more attractive tank, but also a healthier one.
Breeding Cory Catfish
At some point, most Corydora owners want to breed their fish – luckily, breeding Cory Catfish is actually pretty easy.
In this section, we go through everything you know about setting up a breeding tank, encouraging spawning, and raising Cory fry.
Cory Breeding Setup
A huge part of successfully breeding Corys is having the right setup – after all, fish don’t spawn unless they feel comfortable and secure. Here are a few ways that you can approach putting together a breeding tank:
- Strategy #1 – Dedicated Breeding Aquarium: Most breeding guides will tell you that you need to set up a dedicated breeding aquarium separate from the “main” Cory tank. These tanks are usually bare and rarely have any substrate (which makes it easy to clean & raise fry in). This strategy involves removing the Cory breeding group from the main aquarium, acclimating them to the new tank, and encouraging them to breed. Once spawning is finished, the Corys are placed back in the main tank with the eggs being left behind in the breeding tank. This approach works best for those that are serious about having a high fry survival rate.
- Strategy #2 – Dedicated Fry Aquarium: With this strategy, Cory owners induce spawning in the “main” aquarium instead of transferring their fish to a breeding setup. Once spawning occurs, the eggs are transferred to a fry tank where they are hatched and raised. This setup is simpler and less stressful for your adult Corys – that said, fry survival rate tends to be a little lower than with strategy #1.
So which strategy is better? Of course, it depends.
The dedicated breeding tank route is great for those who keep their Corys in community aquariums. While they will still spawn with other species present, tank mates (and even the Corys themselves) will make a quick snack of the eggs.
In addition, having a dedicated breeding aquarium means that you won’t have to move the eggs/fry, which helps increase fry survival rates.
That said, moving your breeding colony back and forth from the main aquarium to the breeding tank can be very stressful for your Cories.
Personally, I prefer going with strategy #2 – I find it to be easier and safer for my fish. I may take a few tries to get the fry tank just right, but once your Cories start breeding you definitely won’t have any shortage of eggs.
Setting up a Fry Tank
Ideally, the fry tank should be set up early in the process – you want to give the aquarium enough time to stabilize before adding any delicate fry.
It may be tempting to add plants, decorations, and substrate to the fry tank, but that’s the exact opposite of what you should do.
The fry tank should be as simple as possible – completely bare is my preference. A bare aquarium is extremely easy to clean, which makes it much easier to keep water parameters stable (which is vital to keeping fry alive).
A 10 gallon aquarium should be fine starting out. Use water and filter media from the main tank – rub the filter media on the tank walls and anything else in the aquarium.
By transferring enough beneficial bacteria, you can completely skip the cycling process in the new fry tank.
For filtration, definitely go with a sponge filter. Anything else will likely be too strong and suck up the baby Cories. I suggest the Bacto-Surge High Density Sponge Filter.
The Bacto-Surge High Density Sponge Filter is the perfect choice for any fry tank. The high-density sponge is gentle, yet allows for optimal beneficial bacteria growth which aids in the biological filtration.
Other than the bare aquarium, sponge filter, and heater, not much else is needed for the fry tank. Like we discussed above, try to keep it as simple as possible. Make sure that there are no traces of ammonia/nitrite and try to keep nitrates under 10ppm.
Determining the Gender of Corydoras
You’re going to need a mix of males and females if you want your Cories to breed (duh). Ideally, you want about 2 males for every female in the aquarium.
Unfortunately, there is no cut and dry method to determine the sex of Cory Catfish with 100% accuracy. That said, there are a few things you can look for.
Male Cories tend to be thin and “streamlined”. Females, on the other hand, are thicker around the midsection and tend to sit higher off the bottom.
Cory Catfish usually can’t be reliably sexed until they reach maturity, so don’t panic if you can’t get a good idea of genders at the fish store.
Instead of stressing out about determining genders right then and there, picking a random group of 6-8 Cories works just about every time.
Here are the chances of getting at least one male/female pair based on the number of fish you buy:
- 6 Cories: 98.43% of at least one pair
- 7 Cories: 99.21% of at least one pair
- 8 Cories: 99.60% of at least one pair
Conditioning Your Catfish
Well fed Cories are happy Cories – therefore, a high protein, nutritious diet is important in the spawning process. Feed your fish a mixture of live/frozen foods such as brine shrimp and bloodworms along with high-quality pellets or flakes.
I prefer to feed small quantities often throughout the day (maybe 4-5 times). Frequent feedings help signal that there’s no shortage of food, which helps induce breeding.
That said, make sure not to overdo it – keeping your water parameters in line should always be the #1 priority.
After a week or two of conditioning, you will notice your female Cories getting plump with eggs. This is a great sign and signals the perfect time to move on to the next step.
Inducing Your Cory Catfish to Spawn
Now that your Cories are well-fed and plump full of eggs, it’s time for the spawn! Some Cories will spawn without any enticing…other won’t.
For those that fall into the latter category, here is a trick that usually works without fail.
Do a large water change (25%-50%) with water that is slightly colder than your tank water (2-3°F cooler). The drop in temperature simulates summer rainfall, which is when Cories breed in the wild.
If your Cories don’t spawn within a few hours, empty out a bit more water and repeat the process again. Never let the water temperature get below 65°F.
Your Cories will most likely spawn the same day, but sometimes it takes a few days – don’t worry if it doesn’t happen right away.
Females usually lay their eggs on the tank wall, but sometime use plants, filters, or decorations instead (I have even seen them lay eggs on an Mystery Snail).
Caring for Cory Catfish Eggs
So you found eggs plastered all over the tank wall…what do you do now?
The first step is getting the eggs out of the main tank – the breeding colony of Cories are hungry after spawning and will usually eat their own eggs.
Use you finger, a credit card, or a razor to gently scrape the eggs off of the tank wall into a small container or net. Be very gentle with this step.
Next, transfer the eggs to the fry tank without exposing them to air. Don’t just throw them in the bottom of the tank though – put them in a breeder net with an air stone for water flow.
If you want something more official than a breeder net, egg tumblers are a great affordable option. They were designed specifically for the purpose of incubating fish eggs and do a great job at deterring fungus. I highly suggest the Cobalt Aquatics Egg Rocker.
Note: If you notice any eggs that turn white/fuzzy, remove them ASAP. These eggs are infertile and growing fungus, which can spread to good eggs given enough time.
Cory eggs usually hatch in 3-6 days. For the first few days, feeding your fry is unnecessary since they absorb nutrients from the egg sack attached to their body.
Once the egg sacks are absorbed and the fry are free swimming, start them on New Life Spectrum Fry Food. I’ve found this to be the most effective and easy to use food (much easier than raising your own baby brine shrimp). Dissolve a small pinch in a tiny bit of water and use a syringe/baster to squirt it as close to the fry as possible.
Your fry should start growing fast once they begin eating. It’s tempting to feed them a million times a day, but make sure you don’t dirty up the tank – fry need pristine water conditions to survive.
Once they are large enough, switch the fry over to dried brine shrimp or crushed up flakes. Try to add some variety in their diet early so they’re not picky later on (which shouldn’t be hard with Cory Cats).
At 3/4″ to 1″, you should be able to transfer your fry to the main tank, trade them for other species, or even sell them to your local fish store!
Frequently Asked Questions
A minimum tank size of 20 gallons is recommended for Corydoras.
Most Corydoras species stay between 2″ to 2.5″. Some species, such as Pygmy Corydoras, only get to about 1″ in length.
Corydoras are scavengers and do best on a mix of plant and meat based foods.
Cory Catfish are a schooling species and should be kept in groups on 5 to 6.
Corydoras in community tank breeding
When one is trying to breed Corydoras, a special breeding tank will usually give better results than waiting for them to spawn in the community tank. Even if they do spawn in the community tank, it is very likely you will not notice it at all.
The eggs are well hidden by the fish, and even if the eggs survive the hungry attentions of the co-inhabitants of the tank and the parents themselves, the larvae coming out of the egg are extremely vulnerable. The first thing they have to do when emerging from the egg is to go up for air to fill the swim bladder. Still, some may occasionally survive this, and after a month or three the owner will be in for a surprise when the first 2 cm long juvenile calmly cruises the tank for food.
Let's assume you plan to breed a particular species of Corydoras. The general tank set up will be described below.
The following information is not a must, but are things that have worked for me, or which I've read. By no means expect your fish to start breeding immediately, even after you've invested a lot of money to copy the described tanks, materials and fish.
The Tank[edit | edit source]
A Corydoras breeding tank should be long enough. As a rule of thumb, length of the tank should be at least ten times the maximum size of the adult fish. There have been numerous reports about full grown Corydoras paleatus spawning in a 30cm (11.8") tank or even smaller, but of course no-one reports the failures. Take it from me that the bigger the tank, the higher the success rate.
Height of the tank should not exceed 30cm (11.8"). (The tank could be higher, but then simply do not fill it up over this height).
The fish[edit | edit source]
This is one of the most important issues, although it's hardly ever mentioned in any set-up information. Of course the fish have to be healthy. And yes they should be fed well. But that is about all that is mentioned.
First things first. A group of fish should be selected, and they should be mature enough. The best way is of course to buy full-grown wild-caught fish. If you buy wild-caught fish, the first thing to do is to make sure they are disease free. During transportation the fish are usually treated really badly.
Some medications used on fish will render them temporarily infertile, which is one of the reasons why so many first spawns go bad. (Although some people theorize this to be a learning process for the fish - nicely thought of by humans, but in free-laying species there is no feedback to the parents that the eggs are not fertilised, so how could they learn?)
Large fish (the ones we want) are usually more expensive because of the higher death rate during shipping (lower water to bodyweight ratio) and because the shop owners know. Do not believe shop owners, they will try to get as much profit from sales as possible. Prices tend to sky-rocket for the people they know will buy this or that new or rare cory.
Do not under any circumstance buy only three fish because they are expensive, and another three in a month's time. There is no guarantee they will be the same species, or type locality.
Small fish will also grow big, although for most species it takes a minimum of two to three years to reach a reasonable size, and growth rate is reduced in tanks when compared to nature.
The décor[edit | edit source]
If you'd like a nice looking tank, you are not going to like this part. Don't worry, the fish tend to breed in those as well. Hiding places: one will suffice - a coconut shell, or better yet create a cave with multiple exits by placing a flat stone on some smaller stones. Plants are optional, but not essential.
The lighting[edit | edit source]
Twelve to thirteen hours of light, preferably subdued light, or no light at all if the tank is near a window.
The substrate[edit | edit source]
Should be sand, approx. 0.5-1cm (0.2-0.4") layer.
The filtration[edit | edit source]
Strong filtration, especially in one area of the tank. But there should be areas where there is little or no current, so the fish can rest.
The temperature[edit | edit source]
Water changes[edit | edit source]
Daily 50% water changes with pre-treated water, approximately 5-10°C (41-50°F) colder than the water in the tank. Be careful when changing the water - if a part of the glass is directly exposed to 10°C (50°F) colder water, it may break!
Feeding[edit | edit source]
Feed the fish well, as much as they like and more. (You're doing daily water changes, so any left overs are no problem). Feed them with red mosquito larvae (bloodworm), blackworms, daphnia, artemia, chopped earthworm and tubifex.
If you keep this up for a week or two (or longer) most Corydoras will spawn . Some require more attention, and should be kept in soft, acidic water for a while. Then change the water with soft, neutral water, to get both a rise in pH and a drop in temperature.
Eggs[edit | edit source]
Be very careful when handling the eggs. The best thing to use is spawning mops, which will enable you to remove the eggs from the tank without handling them. Place the eggs in water taken from the spawning tank into a small holding tank. Still, many eggs may fungus, and most of the times the fish have a mind of their own as to where the eggs should be laid.
If you have to remove the eggs by hand, wash your hands thoroughly before removing the eggs (making sure that no soap remains on your fingers). Some people use a razor blade to remove eggs from the glass, but I've never been able to do that right. Corydoras eggs are extremely hard, and you cannot squash them by handling them.
Back to the eggs fungusing. Eggs fungus as a result of bacterial attacks, which results in the shells being damaged. The fungus is the second infection, because it attacks damaged eggs. Most of the times that I tried to raise the eggs in a separate raising tank, 60-80% of the eggs fungused. Adding a preventive medicine like methylene blue helped a bit to increase hatch rates.
Later I started using breeding nets, which hung from the side of spawning tank. Hatch rates raised to around 90-95%. I keep the fry there, feeding them artemia, for a week or two, and then I transfer them to a raising tank.
Raising Fry[edit | edit source]
Using a pure glass bottom in a raising tank may seem to be a good thing to do, since it's easy to clean. But in my case the fry often developed fungus. In a glass-bottom tank a thin layer of bacteria will always be present, which may cause this. After I added a thin layer of sand, the fry stopped developing fungus.
It's a really nice sight, having an 80cm (31.5") tank filled with over 100 juvenile Corydoras (in my case panda). You can observe some natural schooling behaviour, and watch them eat and grow. They can grow quite fast up to 2-3cm (0.8-1.2") (depending on the species), but after that growth comes to a halt, and it may take up to a year before the fry are the same size as the juveniles you mostly see in the shops. It will take at least a year more for them to become fully grown.
Credit[edit | edit source]
Written by Eric Naus of Amsterdam, Holland in May 2005, Aquaworld.
Article reproduced from AquaArticles and advised.
Layout and wikified by --Quatermass 16:36, 4 January 2009 (UTC)
Further Websites[edit | edit source]
References[edit | edit source]
Article © Ian Fuller, uploaded January 01, 2002.
When first starting keeping tropical fish the majority of people never give a thought to breeding them and their first experience comes when their female Guppy or Platy gives birth to a batch of youngsters. Watching a female livebearer deliver her young is an awesome sight the first time you see it happen and has probably been the beginning of many a lifelong journey for budding aquarists. It was certainly what started me on the road to fish breeding.
Among the many groups of fish that I have bred over the years it's the group of small armoured catfishes from South America belonging to the family Corydoradinae that have intrigued me the most and for the longest time. In fact my interest in them started within the first three years of taking up the hobby, it's an interest that has continued to this day.
There are nearly one hundred and fifty described species, with almost as many more species awaiting scientific description. At any one time there are probably twenty to twenty five species available to the hobbyist, these range in size from a little over one inch body length (25 mm), to four inches (100 mm). Their body shapes also vary, which is an indication that although they belong to the same family they do not necessarily live in the same type of habitats. Which means that providing the correct breeding conditions for them is not always a simple task. The substrate where most Cory's are found is sand and unlike common building sand, river/stream sand is different, because it is constantly being move by the flow of the water the granules have been worn rounded and smooth. In some areas there are larger gravel and in others the substrate is clay, which is not an ideal substance to use in the aquarium. In slower moving rivers, streams and flood plane pools and lakes, there may be thick layers of leaf litter or even deep silt. Therefore selecting the correct substratecan be a problem.
Water condition requirements also vary from species to species, at one end of the scale there are some that require very soft acidic water (0 - 2 dGH; pH 5.6 - 6.0) and at the other end the water needs to be medium hard and neutral (8 - 12 dGH; pH7.0). As aquarists it's almost impossible to determine the exact needs of each individual species, so we need to have to starting point. I would normally start with what I call a basic set up, the size of the tank is not that important, most of my Cory breeding tank are quite small, holding between six and eight gallons of water.
The first decision is to select the species you want to breed and here I would recommend one of the so called easier and more readily available species. Corydoras aeneus the 'Bronze Cory' and Corydoras paleatus 'Peppered Cory', there are also albino forms of both species available, which are equally as easy to breed, the ideal breeding group for any of these species would consist of two females and four males. To house them, an aquarium of 18" x 12" x 10"/12" deep (45 cm x 30 cm x 20/25cm) would be a suitable size for a breeding set up. For those of you that have a limited amount of room there are one or two dwarf species that are also very easy to breed, these are Corydoras habrosus and Corydoras pygmaeus. A small 10" x 8" x 8" (25 cm x 20 cm x 20 cm) aquarium would be an ideal size for these species.
No more than a three eighth of an inch (10 mm) layer of smooth grained sand should be used as a substrate for the larger species and about half that for the dwarf species. The reason for the shallow depth of substrate is so that when the adult fish are sifting through it in their constant search for food, they can actually penetrate to the base of the aquarium. Which alleviates the risk of uneaten food causing pollution problems. By way of filtration I would recommend the use of air driven sponge filters, these once they have matured not only do they help to keep the water clean with their biological action, but provide what can only be described as a dining table for small fry. To mature new filters I set them up in an already established tank, usually the stock tanks that house the fish I want to breed.
The only other additions I would add to a breeding tank would be either a floating spawning mop, constructed out of synthetic 4ply knitting wool. To make a spawning mop simply take a piece of stiff card about 18 - 20 cm wide and wind the wool around it fifty times. Tie off the loops at one end of the card and then cut through the strand at the other, attach a piece of cork to the tied off end and you have a spawning mop. The colour of wool is immaterial but I find that dark green or brown seem to be favoured more than any other colour. Once the mop has been soaked it will provide an ideal egg deposit site. Java moss and Java fern also make good spawning sites; both plants are hardy and will tolerate being moved from tank to tank as required.
A new breeding tank set up will have thin layer of well washed sand, water will be taken from the stock tank that the potential breeding stock are housed in, filling the tank to about three quarters full and toped up with new water of the same temperature. One or two sponge filters are added depending on the tank size and the species to be housed. The temperature is set to suit the species to be bred and then the tank is left to settle for a couple of days. For C. paleatus the temperature would be set at 70° F (21° C), for C. aeneus a little higher at 75°F (24°C), once the tank has settled the adults are introduced. If the water parameters in the stock tank are different to those in the breeding tank the adult fish should be acclimatised, which is done by catching the fish and putting them in a container with water from the stock tank and floating it in the breeding tank. The water in the container is then slowly exchanged for water from the breeding tank; once the acclimatisation has been achieved the group of adults can be released.
Now the potential breeding group need to be given the best diet possible get them into the best possible condition for breeding. A staple daily diet of a quality flake or tablet food alternated with live or frozen foods. Daphnia, Tubifex, bloodworm or Cyclops would be ideal.
Thirty percent water changes should be make twice weekly to keep conditions at there best, making sure to siphon all the fish waste and any debris that has accumulated on the bottom. In many cases when the fish are in the best possible condition a basic water change will be enough to trigger them into spawning mode, some species however will need a little encouragement, which may be achieved by a fifty percent water change using replacement water that is about 10° F cooler (6.5° C). Other species may prove even more difficult and daily water changes may be needed to start spawning interest. It's usually at this point that I advise people to make notes of what they are doing and to record all relevant details, such as tank size, water parameters, food and feeding regime, water changes; how often, how much and temperatures etc. Another tip here is to only ever change one parameter at a time because by altering more, one thing could counteract another.
It will be pretty obvious when the fish are interested in breeding buy their increased activity, what usually happens is the males will start to pay a female a lot of attention by performing little dances around and all over her, often offering themselves in arched sideways stances in front of her. They will stay in constant contact in an attempt to arouse a female's interest. It may only be one two or all four males taking part in the ritual each one competing for the chance to mate. The females will be more interested in cleaning various sites around the tank in readiness to deposit her egg/s. When a female is sufficiently aroused the roles are reversed and she will pursue the male of her choice, nuzzling into his side just above his ventral fins. At this point the male will clamp the females barbels to his side using his pectoral fin spine, the male will be seen quivering for a second or two before releasing his grip on the female. This is what is known as the Corydoras 'T' mating position and depending on the species is the time when the female releases egg/s into a pouch formed by clamping her ventral fins together. There are some species where the female releases her egg/s into the pouch after the male has released her. There is a lot of conjecture how or at what point the egg/s are fertilised and has been the subject for some lengthy discussions, which I do not intend to delve into here.
After mating the female will rest momentarily and then swim off in search of a suitable site to deposit her egg/s, which may be on the tank glass or on one or all of the other tanks furnishings. I have found that C. paleatus seem to prefer the tank sides to deposit their eggs on, with C. aeneus having a preference for plants and mops. Egg size varies form species to species; the smallest I have measured was from Corydoras pestai at 0.7 mm diameter and the largest from Corydoras 2.8 mm diameter. The size and the quantity of eggs seem to be related, a species laying small eggs produces large numbers and a species producing large eggs only produce small numbers. Once the spawning activity has ceased it is best to remove either the adults or the eggs to avoid any possibility of the eggs being eaten, if there are a large number of eggs it is best to remove the adults and return them to their original stock tank. A small number of eggs can be housed in a small container left floating in the spawning tank, where eggs have been deposited in the mop or on the plants it's a simple case of lifting the whole plant or mop out and putting it in the container. Eggs that have been placed on the tank sides can be carefully lifted by using a razor blade, some species produce very sticky eggs that are quite difficult to remove and others have hardly and adhesion at all. Eggs that are removed should be put in a small hatching container (I use 1,5 or 2 litre ice cream tubs) with water from the spawning tank and with an air stone added. If the container is floated in the spawning tank it will be maintained at the same temperature. The addition of a propriety anti fungal solution will help keep any infertile eggs from contaminating the fertile ones.
Over the four or five day gestation period the water in the container should changed for water from the spawning tank, which will reduce the content of the anti fungal solution to zero by the time fry start to emerge from the eggs. Once the fry have escaped the confines of the egg membrane it will take a further two to four days for them to become free swimming, the daily water changes should be continued. When the fry can be seen to have totally absorbed the contents of their yoke sac they will need to be supplied with food and there is nothing better to start them off than small helpings of micro worm, here the term little and often should apply but this is not always a practical option. Therefore feeding twice a day will suffice making the daily water change before the second feeding. After two days of micro worm other foods should be introduced, preferably live food, newly hatched brine shrimp or cyclops are ideal. Pre-soaked powdered flake can also be given alternating with the live food. At this time it will be necessary to increase the amount of water changes to before each feeding.
Corydoras paleatus fry grow very quickly and within four or five week the fry will need to be moved to larger accommodation and by the time they are ten weeks old they should be about one inch in body length.
Finally do remember to keep notes because not everything you do will go according to plan and the record you keep may be invaluable at a later date.
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