How Many Cory Catfish in a 29 Gallon Tank? 12

Last Updated on August 1, 2022 by cmoarz

It’s a pretty straightforward number. You should not have more than 12 cory catfish in a 29 gallon tank. This will allow your fish to have plenty of room to swim and explore their environment without feeling cramped.

However, there are a few things you should consider when adding this many fish to your tank.

Can I put less than 12 cory catfish in a 29 gallon tank?

Yes! You don’t need to keep the maximum number of corydoras in your tank if you don’t want to. A smaller number will do just fine, and your fish will still be happy and healthy.

The only caveat is, that corydoras need to be in groups of 6 or more. So the bare minimum you could get away with would be 6 cory catfish in a 29 gallon tank. But we don’t recommend going any lower than that.

Can I keep anything else in the tank with 12 cory catfish?

Yes. Corydoras take up the bottom of the tank, so you’re free to add other fish that occupy different levels of the water column. Just be careful not to overcrowd your tank.

The most important factor to consider when stocking a tank is the bioload. This is the amount of waste that your fish produce. Too much waste can lead to water quality problems, so make sure you do your research before adding any new fish to your tank.

If your tank is equipped to handle a larger bioload, then feel free to add more top and middle column fish. To achieve a higher bioload maximum, you need plenty of plants and a powerful filter as well as a deep substrate for lots of beneficial bacteria to grow.

Additional water changes will be required the more fish you have. The best way to know how often you need to change the water in your tank is to test periodicity and keep an eye on your fish’s health.

Corydoras are peaceful fish, so they can be kept with a wide variety of tank mates. They are none aggressive and none territorial.

Just make sure to do your research so you don’t overcrowd your tank and cause water quality problems.

What else you will need to add to the aquarium for your corys

First, make sure that you have a good filtration system in place. This will help to keep the water clean and free of harmful toxins. Make sure the tank is fully cycled as well. 12 cories have a fairly significant bioload.

This bioload is increased the more middle and top column fish are added to the aquarium.

Second, you’ll need to provide plenty of hiding places for your fish. Cory catfish are bottom dwellers and prefer to hide among plants and rocks. If you don’t have any plants in your tank, you can add artificial plants or live plants. But we highly recommend real living plants because they do wonders in helping keep the tank clean.

Third, you’ll need to add a deep substrate to the bottom of the tank. Cory catfish like to sift threw the substrate and it also provides a place for beneficial bacteria to grow. A deep substrate also helps to buffer the pH of the water and keep it stable.

Many other places will recommend 3 inches of substrate, But at we always recommend 6 inches. The extra substrate helps keep the tank cleaner and allows for much more buffer against a sudden pH drop, as well as lots of space for plants to expand their roots.

You’ll need to provide some form of lighting. Cory catfish are not picky about lighting and will do fine in most aquariums. But we recommend using a low to moderate light level. This will help to keep the algae growth under control and also make your fish more comfortable. Corydoras do not like bright lights.

And lastly, make sure to do plenty of research before adding any new fish to your tank. Cory catfish are peaceful fish, but not all fish are compatible with them. Some fish can be aggressive or territorial and this can cause problems in the tank.


Owner of and also owner of actual Aquarium Gravel believe it or not! ;). Setting up beautiful aquarium sceneries and habitats since I was very young. Enjoy!