Overview
The African Arowana (Heterotis niloticus), also known as the slape, is the only extant representative of the family Arapaimidae native to the African continent. Closely allied evolutionarily to South America’s colossal arapaima, this ancient osteoglossiform fish navigates slow-flowing rivers, seasonal floodplains, and reed-choked lagoons across the Sahel and West Africa, possessing unique respiratory and feeding adaptations that have endured since the age of dinosaurs.
Biology and Physical Characteristics
Attaining lengths near one meter, Heterotis niloticus features an elongated, heavily armored cylindrical body encased in large, mosaic-like cycloid scales that range from bronze to smoky olive-gray. Unlike South American arowanas, it possesses a terminal, rounded mouth equipped with a specialized suprabranchial spiral organ. This intricate, snail-like structure allows the fish to filter-feed on microscopic plankton, algae, and detritus while also acting as an accessory breathing apparatus to extract oxygen from atmospheric air in stagnant, hypoxic waters.
Behavior and Ecology
African arowanas exhibit remarkable reproductive behavior and parental investment. During the wet season flood pulse, adult pairs excavate large circular nests up to four feet in diameter within shallow, weed-choked marsh beds, constructing tall walls out of trampled aquatic reeds. Following spawning, both parents zealously guard the developing eggs and fry against predators, guiding dense schools of hatchlings through the vegetation until the juveniles can fend for themselves.
Conservation and Human Impact
Assessed as Least Concern by the IUCN, Heterotis niloticus is widely distributed throughout major river systems including the Niger, Senegal, Gambia, and Nile, and has been successfully introduced into several inland reservoirs and aquaculture facilities. While overfishing and seasonal wetland drainage represent localized challenges, wild populations remain resilient throughout protected river basins.
Interesting Factoid
Unlike predatory South American arowanas that jump from the water to snatch birds and bats from low branches, the African arowana is a gentle giant equipped with a spiral filter in its throat to strain plankton and mud from river bottoms!
Last updated: October 2026