Apistogramma-nijsseni is a species of small, colorful cichlid fish native to South America. It grows up to three inches in length and has a unique, bright yellow and black pattern. The fins are long and pointed, and the males have an extended dorsal fin. These fish are very active and social, and form large schools when in the wild. They are also very territorial and will defend their territory against other fish. They prefer soft, acidic water, and need plenty of hiding places, such as caves and driftwood, to feel secure. Apistogramma-nijsseni is a great choice for the avid aquarist looking for a bright, active fish.