How many corydoras to keep?

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onyxim
Posts: 5
Joined: Thu Oct 10, 2024 7:07 pm

How many corydoras to keep?

Post by onyxim »

I've got a 20 gallon tank with sand substrate and a sponge filter. Wanna add some Corydoras but not sure how many to start with. Heard they like groups, but don't wanna overcrowd. What's the sweet spot?
haply
Posts: 9
Joined: Thu Oct 10, 2024 3:34 pm

Re: How many corydoras to keep?

Post by haply »

For a 20 gallon, I'd recommend starting with 6 Corydoras. They're social and do better in groups. Make sure your tank is cycled and has plenty of hiding spots. Sand is perfect for them since they like to sift.
frosta
Posts: 5
Joined: Thu Oct 10, 2024 4:01 pm

Re: How many corydoras to keep?

Post by frosta »

I agree with haply. Six is a good number. They'll be happier and more active in a group. Just keep an eye on your water params, especially nitrates, since they can be sensitive.
onyxim
Posts: 5
Joined: Thu Oct 10, 2024 7:07 pm

Re: How many corydoras to keep?

Post by onyxim »

haply wrote: Fri Jun 20, 2025 9:31 am For a 20 gallon, I'd recommend starting with 6 Corydoras. They're social and do better in groups. Make sure your tank is cycled and has plenty of hiding spots. Sand is perfect for them since they like to sift.
Thanks! I'll start with six then. Got some driftwood and plants in there too, so they should feel at home.
haply
Posts: 9
Joined: Thu Oct 10, 2024 3:34 pm

Re: How many corydoras to keep?

Post by haply »

Sounds like a great setup. Just remember to acclimate them slowly. Corydoras can be a bit sensitive to sudden changes. What other fish are in the tank?
frosta
Posts: 5
Joined: Thu Oct 10, 2024 4:01 pm

Re: How many corydoras to keep?

Post by frosta »

Yeah, slow acclimation is key. I've lost a few Corydoras in the past by rushing it. Now I always drip acclimate for at least an hour. What's your water temp?
onyxim
Posts: 5
Joined: Thu Oct 10, 2024 7:07 pm

Re: How many corydoras to keep?

Post by onyxim »

It's at 76°F right now. Got a couple of neon tetras and a betta in there too. The betta's pretty chill, so I'm not too worried about aggression.
haply
Posts: 9
Joined: Thu Oct 10, 2024 3:34 pm

Re: How many corydoras to keep?

Post by haply »

onyxim wrote: Fri Jun 20, 2025 11:42 am It's at 76°F right now. Got a couple of neon tetras and a betta in there too. The betta's pretty chill, so I'm not too worried about aggression.
That temp is perfect for Corydoras. Just watch the betta, even if it's chill. Sometimes they can get territorial with bottom dwellers.
frosta
Posts: 5
Joined: Thu Oct 10, 2024 4:01 pm

Re: How many corydoras to keep?

Post by frosta »

I've had mixed results with bettas and Corydoras. Some bettas ignore them, others chase. Maybe add the Corydoras first and see how the betta reacts before adding more.
haply
Posts: 9
Joined: Thu Oct 10, 2024 3:34 pm

Re: How many corydoras to keep?

Post by haply »

Good point, frosta. It's always better to err on the side of caution. How often do you do water changes, onyxim?
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