This guide will help you understand which fish and other critters are suitable, and the best fish for your 5 gallon tank. Chili Rasboras (Boraras brigittae) ... Endler's Livebearer (Poecilia wingei) ... Fancy Guppy (Poecilia reticulata) ... Betta (Betta splendens) ... Killifish. ... Dwarf Pea Puffer (Carinotetraodon travancoricus) More items... Aug 17, 2022