How Many Cory Catfish in a 10-Gallon Tank?

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Corydoras are peaceful bottom dwellers that won’t grow past 4 inches. Many of them remain between 1.5 and 2.5 inches, depending on the breed, environmental conditions, genetics, food, etc.

They’re also not that active to begin with, spending their time near the substrate and in hiding.

So, it’s easy to think that they don’t need much space and could easily adapt to smaller setups. But how small are we talking about exactly? Let’s have a look!

Can Corys Live in 10-Gallon Tank?

Yes, but only when it comes to smaller breeds, up to 2 inches in size. You can theoretically keep one larger cory catfish in a 10-gallon tank, but that’s far from optimal for several reasons.

One of them is that Corydoras are social animals, so they like company if possible. The presence of other corys keeps them calmer and healthier in the long run.

Another reason would be the need for decorative elements designed to make the catfish feel safe and at home.

Then you have the live plants and tank equipment to fit in as well. So, a 10-gallon tank is only fit for smaller breeds, and not even that is optimal.

Number of Corys for 10-Gallon Aquarium

As a general rule, you can fit up to 4-5 smaller cory breeds in a 10-gallon setup. We’re talking about pygmy and dwarf varieties that don’t need that much space, to begin with.

Pygmy Corydoras, for instance, grow between 0.75 and 1 inch, depending on the fish’s sex.

Larger Corydoras naturally require more space, so the 10-gallon tank won’t be enough.

Tips for Keeping Corys in a 10-Gallon Tank

If you only have a 10-gallon tank to work with, you need some work to get the 10-gallon habitat perfect for your Corydoras.

It’s easy to mess things up with such a small space, given that smaller aquariums are more difficult to manage than larger ones.

Here are some fundamental tips to consider:

Cory Types

We’ve already highlighted this point previously. The first step is choosing the right cory breed that wouldn’t mind dwelling in a smaller habitat.

Pygmy and dwarf Corydoras are of similar size, between 0.75 and 1-inch-long, so they will fit right in. You can have several corys in the same tank, which won’t be possible with larger breeds.

However, if you want larger corys, I suggest upgrading your tank. In theory, you can have one larger Corydoras in your 10-gallon tank, but that’s far from ideal.

Your cory catfish will lack the necessary social interactions present in a group and will feel lonely with time. This will decrease the catfish’s quality of life and reduce its lifespan as a result.

Water Changes

Water changes are a necessary maintenance routine meant to preserve the hygiene of any aquatic setup.

You need to perform water changes regularly, no matter the fish species you have, the tank’s size, or how the water looks like visually.

The goal is to reoxygenate the environment, dilute nitrates and other potentially dangerous chemicals, and preserve the system’s stability and cleanliness.

The problem is that smaller environments require more frequent water changes than larger ones. It doesn’t matter that you’re housing catfish which are a cleaner species by definition.

You still need to have a thorough water change routine in place to keep their habitat clean and healthy.

You may need to perform one water change weekly or every 2 weeks, depending on how much mess your fish will produce. Fortunately, corydoras aren’t messy fish, and they even contribute to the system’s stability.

If you have a cory-exclusive tank, you may only need to perform a 15-20% water change every 2 weeks.

But feel free to adapt to your fish’s routine and go for a partial water change whenever necessary.


A good filtration system is vital in a 10-gallon setup and small aquariums in general.

That’s because there’s less room for the naturally-produced chemicals to go, which can cause spikes in ammonia, nitrites, and nitrates over time.

Oxygen levels will also drop faster in a smaller ecosystem, especially when you have several Corydoras around.

Adding more plants won’t help that much either because you don’t want to overplant your cory tank.

Plants produce a lot of oxygen during the day and consume nitrates, true, but they become a liability during nighttime.

That’s because plants actually consume oxygen during nighttime, which can cause spikes of CO2, causing your catfish to risk asphyxiation.

The filtration system will prevent all these issues by keeping the ecosystem stable and fresh.

Just be aware of the following:

  • Adjust the power – You naturally don’t need too much power in a 10-gallon setup, especially since Corydoras aren’t fond of fast-moving waters. Adjust the filter’s intake and output power accordingly to match your catfish’s preferences.
  • Consider the intake’s placement – Place the intake somewhere in the tank’s middle area. You don’t want the intake to suck in plant matter or sand from the substrate, as this can clog the system faster. You should also consider the output’s placement. If it’s too close to the substrate, it will stir up the sand and disturb the fish.
  • Secure the intake – Nano catfish are notorious for getting into hard-to-reach, tight places, and the filter’s intake perfectly matches the description. Use a sponge or a piece of material to block the intake and prevent that. You should check the material regularly to clean or replace it, as it will accumulate detritus and filth and may clog fast.

Live Plants

Corydoras like love plants as they provide them with shelter and a richer playground.

Java fern is particularly great for the catfish, allowing it to navigate its rich leaves for a plus of safety and exploration points.

Just make sure you don’t overplant your aquarium. Corydoras still need their sand substrate to sift through and some rocks and caves to use when stressed or tired.

These fish do best in a diverse and lush ecosystem that mimics their natural habitat, and plants are just one component.


Corydoras are either overfed or underfed, depending on their keeper’s experience with catfish. Some people overfeed them because they’re small and cute and eat non-stop.

Others underfeed them because they believe that catfish get all their food from their scavenging incursions, which is not true. Catfish require a stable diet to remain healthy and happy.

But too much food can also cause them harm. Overfeeding leads to bloating, which is responsible for swim bladder disease, obesity, and constipation, depending on the case.

You shouldn’t feed your catfish more than twice per day and only in small portions that the fish will consume in less than 2-3 minutes.

Always assess your fish’s eating habits to learn its feeding behavior and appetite.

Ideal Tank Size for Corydoras

If you can choose, I say choose something bigger than 10 gallons. You should go at least 20 gallons for a group of 6 corydoras, including larger specimens.

Large varieties, closer to 4 inches, may need slightly more space, around 25-30 gallons.

Especially if you keep them in groups larger than 6 individuals.


Corydoras aren’t too active, to begin with, which might lead you to think they don’t need that much space.

This is only partially true, as we’ve already discussed.

Space is critical for the fish’s mental state, given that this is a social species that thrive in groups.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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