Stop. You already have a ton of fish in your tank.

Betta's are solitary fish and very aggressive toward other fish. They need to be kept in their own tank.

I've read somewhere that a good rule of thumb is one inch of fish for each gallon, so 10 two inch fish max for 20 gallons. But less is better or you will have ammonia problems. I wouldn't put anymore fish in your tank.

Thats what my gut said too ... :(

Hi
no more fishin the tank. With what you have now, problems will arise. No red-tailed black shark either. They get to large for your tank and they are not the best choice for a community tank.And as for the 1 inch per gallon, that does not work either, for example a 2 inch gourami has a much bigger body than a 2 inch molly yes you could put 10 mollies in a 20 gal tank but would you put 10 gouramis in the same size tank

its too many already

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