Garuf said:You'll always be limited to smaller fish in a 20g but that doesn't mean necessarily neon tetra sized fish. I assume you're looking for something deeper bodied? If so there are a lot of deep bodied tetras that would be suitable. X rays or black phantoms spring to mind straight away. Is this what you mean?
Gill said:Depends on whether you want the new addition to co-habit with current tank mates.
nry said:Some of the smaller gourami? Things like rams are nice too, very brightly coloured and a good size for a 20g