Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
A 5 gallon is pretty small, so small fish only (shrimp, nerite snails OK).
A small school of dwarf Rasboras, Clown Killies or similar sized fish. These are smaller than 1/2". Half a dozen (with shrimp) to a dozen (no shrimp) is OK in a 5 gallon. A few dwarf Cories (C. habrosus, pygmaeus or similar size)
A single Betta, perhaps a snail is OK, but Bettas often eat shrimp. Not always. Some do not. I would not add high priced shrimp, though.