The Cory catfish, otherwise known as the Corydora, is, in my opinion, the coolest freshwater schooling fish that is realistic to keep in a home aquarium. Now, I know there are fish like Neon tetras or Cardinal tetra that, when in a school, they look extremely cool, but I think these little guys are just so unique.
The Corydora is my favorite schooling/shoaling fish, where shoaling means they are a very social fish. There are definitely a few reasons for that. One of the reasons would be that they are also bottom feeders. Most of the schooling fish, such as cardinals or neon tetras, are not really bottom feeders; they tend to stay near the middle of the tank. But with the Corydoras, they stay near the bottom, cleaning up whatever extra food they can find, just like a few tank janitors. This makes your job of maintaining a clean tank a little bit easier. Corydoras have things by their mouth called barbels; they use these barbels to dig through the substrate to find food. So you will want to have substrate that is smooth so your Corydora won’t damage their barbels. I would recommend, if you’re keeping Corydoras, to use sand as their substrate, as I have seen it is the easiest substrate for them to dig through.
About the Corydora
Corydoras should only be kept in groups of six or more; the more you can keep, the better the result you will get. If you have the resources to keep say maybe 30-50 of them in the same tank, I say you definitely should. When these guys are together in big groups, they are very active and social fish, very cool to watch. With Corydoras, it’s not necessarily about tank size; it’s more about how much of your tank bottom is free. Well, if you have a 20-gallon tall, it’s not gonna have as much floor space as a 20-gallon long would have. I’d recommend for a 20 long to keep 6-8 1-2 inch Corydoras. If you have a 20-gallon long, then you should be able to keep anywhere from 5-10 1-2 inch Corydoras.
Types of Corydoras
There are plenty of different kinds of Corydoras, the most popular in no particular order being Panda Corydora, Bronze Corydora, Sterba’s Corydora, Pygmy Corydora, Julii Corydora, Salt and Pepper Corydora, and so many more. My favorite type of Corydora is the Salt and Pepper Corydora, which is the same Corydora shown in the image at the top of this page. I am currently housing Salt and Pepper Corydoras in my 20-gallon tank along with some guppies.
Corydora Water Parameters
Corydoras enjoy a temperature around 75-79°F and a basic pH of around 7-8. Corydoras in the wild usually are in softer water. If your Corydoras are locally bred and not caught, they should do fine in either hard or soft water as long as you acclimate them properly.
Corydoras are very peaceful fish, meaning they can really be put in a tank with almost any other fish. You just have to make sure that the fish in your tank are known to be aggressive. Corydoras are bottom dwellers, so it would be hard to mix them with another species of bottom dwellers. If you’re trying to have two different kinds of bottom dwellers, you need to make sure your tank is big enough for both of them.
Corydoras like all kinds of food, since they’re bottom feeders, they will dig through the substrate to find food. But you can’t rely on the food in the substrate as its only food source; you need to also need to feed it foods specifically for them. Foods Corydoras do best with are bottom feeder tablets or pellets; most sinking foods they will eat. A Corydora food I’d recommend is Omega one sinking catfish pellet.
If you have any questions about corydoras or other questions about fishkeeping let me know in the comments below.