When is a tank overcrowded?

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naturelover
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When is a tank overcrowded?

Post by naturelover »

I've got a 20 gallon tank with 10 Neon Tetras, 5 Corydoras, and a Betta. The water params are good, 0 ammonia, 0 nitrite, but the Betta seems stressed. Is this too many fish?
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Koralin
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Re: When is a tank overcrowded?

Post by Koralin »

naturelover wrote: Wed Jun 25, 2025 11:37 am I've got a 20 gallon tank with 10 Neon Tetras, 5 Corydoras, and a Betta. The water params are good, 0 ammonia, 0 nitrite, but the Betta seems stressed. Is this too many fish?
Yo, that's pushing it for a 20 gallon. Bettas need their space, and Neon Tetras can be nippy. You might wanna consider upgrading or rehoming some fish. Also, what's your filtration like? A crowded tank needs solid filtration to keep up.
mariner
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Re: When is a tank overcrowded?

Post by mariner »

I agree with Koralin. The general rule is 1 inch of fish per gallon, but Bettas are territorial. Your tank is technically within limits, but the Betta's behavior is the real indicator. How often are you doing water changes? More fish means more waste, so you might need to up your maintenance game.
trail8er
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Re: When is a tank overcrowded?

Post by trail8er »

mariner wrote: Wed Jun 25, 2025 12:48 pm I agree with Koralin. The general rule is 1 inch of fish per gallon, but Bettas are territorial. Your tank is technically within limits, but the Betta's behavior is the real indicator. How often are you doing water changes? More fish means more waste, so you might need to up your maintenance game.
The inch-per-gallon rule is kinda outdated, tbh. It doesn't account for fish behavior or bioload. Corydoras are messy, and Neon Tetras are active swimmers. Your Betta's stress is a red flag. I'd say cut the Tetras down to 5 and see if that helps.
Voyager7
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Re: When is a tank overcrowded?

Post by Voyager7 »

Yeah, the Betta's probably feeling cramped. I had a similar setup once, and the Betta was constantly flaring. Moved him to his own 10 gallon, and he chilled out. Maybe try separating the Betta or reducing the school size. Also, what's your tank decor like? More plants and hiding spots can help reduce stress.
bloomi
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Re: When is a tank overcrowded?

Post by bloomi »

I'm new to this, but my Betta was super stressed in a community tank too. Moved him to a 5 gallon solo, and he's way happier. Maybe your Betta just needs his own space? Also, how's the lighting? Bright lights can stress them out even more.
naturelover
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Re: When is a tank overcrowded?

Post by naturelover »

Thanks for the advice, everyone. I'll try reducing the Tetras and adding more plants. The filter is a Hang-On-Back, but I'll look into upgrading it too.
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Koralin
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Re: When is a tank overcrowded?

Post by Koralin »

naturelover wrote: Wed Jun 25, 2025 3:19 pm Thanks for the advice, everyone. I'll try reducing the Tetras and adding more plants. The filter is a Hang-On-Back, but I'll look into upgrading it too.
Solid plan. More plants will help with water quality and give the Betta some cover. If you're sticking with the HOB, maybe add a sponge filter for extra biofiltration. Keep us posted on how it goes!
mariner
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Re: When is a tank overcrowded?

Post by mariner »

Plants are a great idea. Java Fern and Anubias are low-maintenance and provide good cover. Also, consider floating plants like Frogbit. They diffuse light and give the Betta a place to rest near the surface.
trail8er
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Re: When is a tank overcrowded?

Post by trail8er »

mariner wrote: Wed Jun 25, 2025 4:06 pm Plants are a great idea. Java Fern and Anubias are low-maintenance and provide good cover. Also, consider floating plants like Frogbit. They diffuse light and give the Betta a place to rest near the surface.
Floating plants are a game-changer for Bettas. They love lounging in the roots. Just watch out for overgrowth, it can block too much light for the plants below. Also, if you're gonna reduce the Tetras, do it gradually to avoid shocking the tank's balance.
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