Rainbow shark (Epalzeorhynchos frenatum) is a species of Southeast Asian freshwater fish from the family Cyprinidae. It is also known as the ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin shark and whitetail sharkminnow. It is a popular, semi-aggressive aquarium fish. Unlike true sharks, which belong to the Chondrichthyes (“cartilagenous fishes”) lineage, the rainbow shark is an actinopterygiian (“ray-finned fish”).

Distribution and habitat
Rainbow sharks are native to the basins of Mekong, Chao Phraya, Xe Bangfai and Maeklong in Indochina. They live in water with sandy substrates, near the river bottom. This species feeds on algae and plankton, and seasonally migrates into flooded areas, then recedes back to the rivers as the floods dry up.

Description
The rainbow shark has an elongated black, dark blue or bright blue body. 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 about 6 in (15 cm) long