Join Date: Oct 2010
Location: Victoria, Australia
Killies, sparkling gourami, scarlet badis, liqourice gourami, celestial pearl danios and microdevario kubotai are all fish I have kept that can be housed in the 5-10 gallon range (the schooling fish obviously need a larger tank).
Killifish are great and a pair can live quite happily in a 5 gallon tank. You could have a whole group of clown killifish in there if you wanted to. I have four of them in a 2.5 gallon space and they are extremely healthy and active.
Many species that are suitable for nano tanks are quite delicate as mentioned, so you generally need a cycled, established tank before introducing them.