Apistogramma nijsseni is a species of cichlid fish, endemic to highly restricted local black water habitats in the Quebrada Carahuayte, a small stream in the Ucayali River drainage, southern Peru. The male reaches a maximum length of 8 cm (3 in), the female remaining somewhat smaller. Apistogramma brooding females assume a bright yellow and black aposematic coloring: in A. nijsseni, unusually, a healthy, unstressed female retains this coloring. The species is popular aquarium fish amongst dwarf cichlid hobbyists, though it does not often appear in the general pet fish market.