The only rainbowfish that would work well in a 20g tank is pseudomugil gertrudae and it should be kept species only.LIBPA said:I like rainbow fish and tri color sharks, althogh, if you take good care, the tri colored shark can get up to 18-24 inches. Maby get some fancy guppies, there always nice. After my tank was setup with all my fish, i thought that a large school of neon tetras would look really good, but it was too late. I'd go with the neon's.
Roan