The Calvus is endemic to Lake Tanganyika in eastern Africa where it can be found living among the rocks along the shore of the lake. These fish exist in several morphological varieties including black, yellow, white and a black and white striped variant. This species typically exhibits a laterally compressed body which allows it to squeeze into crevices in rocks in search of prey. This body shape also gives the fish an advantage over predators because it makes it easy to spot head-on. Calvus have thick, armor-like scales which can be used as weapons against predators.