Apistogramma nijsseni
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 , 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. The species is named after the Dutch ichthyologist Han Nijssen Apistogramma nijsseni