Silvertip tetra
Silvertip tetra ("Hasemania nana") is a species of characid freshwater fish native to streams and creeks in the São Francisco basin in Brazil, but frequently kept in aquariums. Silvertip tetras are slightly more aggressive than other comparable smaller tetras, observed occasionally to nip other similarly sized tetras. Description. This small fish reaches up to in standard length. The males have a copper color, the females are more pale and silvery. Both have white tips on the fins, hence the name. They differ from most other tetras by lacking a small second dorsal (adipose) fin. Silvertip tetras have a  black area at the base of their caudal fin. The fish are transparent except for the fact that their bodies have an overall copper sheen. During the night, the copper and black become silver as the fish rests — the color is reactivated once the fish becomes active in the morning. Other than coloration, sexual dimorphism is slight, the female having a very slightly larger belly. These tropical, freshwater fish thrive in temperatures that range from 71°F - 82°F (22°C - 28°C). The silvertip tetra lives in slightly acidic waters that range from a pH  of 6.0 - 8.0. These fish like to be kept in schools of 5 or more fish. When held in captivity, the silvertip tetra needs a tank size with a minimum of around 50 litres (10 gallons).