They flourish in cooler waters. They need a high O2 level. They get about 1 1/2 times the size of neon tetras. The best I can do in my tank is room temp so around 72-74 degrees most days. I added extra filtration for water mov't and that really perks them up. I have had them live 5+ years at best.
I have 7-8 currently in a 29 gallon tank with cories and lots of plants. 20 may be pushing it a bit and you will find them less exciting to watch if you stuff too many into too small a tank. They are as fast a swimmer as danios.
I have 7-8 currently in a 29 gallon tank with cories and lots of plants. 20 may be pushing it a bit and you will find them less exciting to watch if you stuff too many into too small a tank. They are as fast a swimmer as danios.