The rainbow shark (Epalzeorhynchos frenatum) is a popular freshwater community-tank aquarium fish of the Cyprinidae family. It is also variously known as the ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin shark and whitetail sharkminnow. Unlike true sharks, which belong to the cartilaginous fishes, the rainbow shark is a bony fish. Rainbow sharks are tank-bottom and aquarium-surface cleaners. Being bottom-level and mid-level dwellers, they consume leftover fishfood. They are known to be territorial, and aggressive to their own species. If kept with their own kind or relatives, threat displays and fighting is likely to occur. This fighting behavior involves head-and-tail butting. Provision of hiding places and hollowed decors such as plants or artificial cave-like and tunnel-like aquatic ornaments minimize this typical behavior. Due to this behavioral characteristic among its own kind, rainbow sharks are not recommendable to the new aquarist. Keeping them with relatives such as red-tailed sharks, and black sharks are avoided.

Rainbow sharks have elongated, dark-black and greenish bodies. The snout is pointed. The abdominal area is flat. The fins possess red to orange-red coloration. The linear area from the gill cover, the eye, and the mouth has a characteristic brief stripe. Compared to females, male rainbow sharks have thinner bodies with black lines along the tailfins. Males also have brighter coloration. They can grow up to 6 inches (15 cm) long with an average life span ranging from 4 to 6 years.

Taken from WikipediA