Corydoras, commonly known as Cory Catfish, is a great addition to any tank. They are bottom-dwellers that are impeccable cleaners and have pleasant demeanors. It is no wonder why aquarium enthusiasts want them in their tanks!
Breeding corydoras in your freshwater tank will require a breeding tank of the correct size, the proper water parameters, a group of corys, and patience! Corydoras are very simple to breed because they typically spawn without any outside help, as long as certain conditions are met.
If you already have a few of these fish, then you know they are a valuable asset in your tank. With some knowledge, any aquarium enthusiast can start breeding corydoras and this is a great place to start!
Tank Requirements for Breeding Corydoras
While not necessary, it is typically recommended to have a separate breeding tank for any fish that you are intentionally trying to spawn. With that being said, you will want to ensure that your tank is big enough for your corydoras to be comfortable and also confirm that your tank parameters are in check.
Size of Tank
Breeding Corydoras is easy, but it is no job for a small tank. While you may think that a 10-gallon tank would be enough; you actually need double the size! A 20-gallon tank is recommended for breeding corydoras.
With that being said, it is better to have a bare bottom tank, meaning no gravel, and low lighting. On top of this, it is also best to add a few live plants and hiding places in the tank so the fish feel safe and have plenty of places to lay eggs.
Tank Parameters
Tank parameters are crucial when breeding any type of fish in order for them to remain healthy. The following table shows what your tank parameters need to be to ensure that your cory catfish are happy and healthy!
| Water Parameters | Range |
| pH | 6.0-8.0 |
| Temperature | 70-80°F |
| Alkalinity | 3°-10°dKH |
Thankfully, checking the temperature does not require any extra effort as thermometers are usually suctioned to the tank. However, in order to test the pH and alkalinity, you will need to purchase testing strips and check the parameters periodically.
Find a Group of Corydoras to Mate
Corydoras are not monogamous nor livebearers. They actually lay eggs which are then fertilized by males. Furthermore, cory catfish prefer to be in groups and not just a single pair; this also pertains to the breeding tank.
Distinctions Between Males and Females
In order to find Corydoras to breed, you will need to know how to tell the difference between males and females. If you purchased your cory catfish from a breeder then you may already know the sexes of your fish, which makes it that much easier.
However, if not, this table will help you identify the males and females. While these qualities are not definitive, they do help. It is also important to know that you can only sex Corydoras once they are mature, which is around 9-12 months of age.
| Male | Female | |
| Body Shape | Slimmer | Less Streamlined with a Prominent Stomach |
| Head Shape | Smaller Gap in Between Eyes | Snout is Curved and Head is Larger |
| Pelvic Fins | Narrower, Pointed | Fan-Shaped |
| Pectoral Fins | More Robust Pectoral Fins, Longer | Much Small that the males, shorter |
| Anal Fin | Pointed Anal Fin | Rounded Anal Fin |
These are all subtle differences between the males and females. If you are still unsure of the sex of your fish, you can stick with the recommended ratio of catfish. As said, corys are school fish and are happiest with more of their own kind.
Ratio of Males to Females Recommended
With corys being school fish, it is essential to have the correct balance of males to females that will result in the most fertilized eggs. In total, 6 or more cory catfish are preferred to be kept together and will have the best results for males and females.
The below table explains:
| Amount of Fish | Chances of Getting Both Males & Females |
| 2 | 75% |
| 3 | 87.5% |
| 4 | 93.8% |
| 5 | 96.9% |
| 6 | 98.4% |
With the correct number of males and females in a proper breeding tank, fertilized eggs are almost a guarantee.
Conditioning Your Corydoras
Food
Once you determine the sexes of your fish, you will want to start conditioning the females to carry eggs. While fish flakes are okay; they are not recommended to feed as the only food source for Corydoras when it comes to spawning.
In order to get the females plump for spawning, feeding them a mixture of brine shrimp, blackworms, or blood worms on top of high-quality flakes or pellets is recommended. This gives them the extra protein needed to lay more eggs.
With that being said. Instead of feeding them two larger meals per day, you should feed them smaller meals throughout the day to cut down on waste and ensure your tank parameters stay where they need to be.
Recreating Amazon Cycles
Corydoras originate from the Amazon and base their breeding habits on the dry and rainy seasons of the area. They typically breed during the rainy season, so if you notice that the fish are not breeding you will want to simulate the dry season.
To do this, you will need to remove about 50-70% of the water from the tank (to mimic a drought) for a few weeks and also remove any live plants. During this time, you will also reduce the amount of food given to the fish.
When the 2 weeks are up, you will then add cooler water back to the tank and start feeding heavily again. They will then think it is mating season and get to work!
How to Know When Your Corydoras are Spawning
Once the females are conditioned and the tank parameters are set, the Corydoras will likely start spawning shortly after. With the correct ratio of males and females, how do you know when your Corydoras are actually spawning?
Corydoras spawn in a rather unique way that is different from other aquarium fish. When ready, the male and female will go into a ‘T’- position, with the male as the base of the ‘T’. He will then release sperm into the female’s mouth, which she will then swallow. When the female swallows the sperm, she is fertilizing the eggs which she will lay shortly after.
Hatching Eggs
Placement of Eggs
Once the eggs are fertilized the female lays the eggs throughout the tank. This can be anywhere from on the tank glass to decorations or rocks. After an hour or two, you have a few options on what to do with the eggs depending on your setup.
You can remove the eggs by gently taking them off the surface with a debit card (or another item that is similar) and putting them in a separate tank. This allows the eggs to hatch within 3-7 days without the threat of being eaten by an adult.
Another option is to remove the adults from the tank. However, this only works if you have a separate tank within the right parameters for the adults to thrive. The last option is to leave the eggs right where they are. While this option is fine, you are taking a risk that something can happen to the eggs.
Hatched Eggs
After the eggs have hatched, the fry will grow quickly. It is important to know that within the first 24-48 hours after hatching, the fry do not need food as they are still feeding off of their yolk sack.
After this amount of time, they can be fed powdered foods, micro worms, and egg yolks. After about a week on these foods, they can then upgrade to baby brine shrimp for extra protein along with regular fish food flakes.
