Pamba

The Pamba (Swahili for ' cotton ' ) is a freshwater cryptid allegedly living in Lake Tanganyika, Tanzania.

Possible explanation
Some researchers have suggested that the Pamba is a Tanganyika lates (Lates angustifrons), a large species of lates perch which is endemic to the lake. As the fish can grow up to around 6 ft in length, it is one of the largest animals that exist in Lake Tanganyika.