Gymnarchus niloticus
FAMILY
Gymnarchidae
TAXONOMY
Gymnarchus niloticus Cuvier, 1829, Nile River.
OTHER COMMON NAMES
German: Nilhecht.
PHYSICAL CHARACTERISTICS
Maximum size 5.48 ft (1.67 m) at 40.8 lb (18.5 kg). Heavy elongate fishes covered with small scales. Have long anal fin tapering in a short caudal appendage, lack dorsal, pelvic, and caudal fins. Caudal part can regenerate after injury. Anal fin used for propulsion. Weakly electric fish.
DISTRIBUTION
Large rivers and back waters of the Sahelo and Sudanian regions of Africa
HABITAT
Back waters with slow-moving or stagnant water, vegetation, and various kinds of cover.
BEHAVIOR
Nocturnal; hides during daytime. Very aggressive towards conspecifics. Weakly electric discharges of the sinusoidal type used for electrolocation.
FEEDING ECOLOGY AND DIET
Piscivorous, ecology not well known.
REPRODUCTIVE BIOLOGY
Breeds in swamps during the high-water season. Prior to spawning, a floating nest of plant fibers is created, most probably by the male. 1,000 or so eggs, each about 0.16 in (4 mm) in diameter, are laid in the nest. The newly hatched young have long gill filaments and an elongate yolk sac. They come to the surface for air. Young fishes feed on insects and other invertebrates. Parental males defend the nest very aggressively and do not hesitate to attack and bite human intruders. It is quite common to see fishermen in West Africa with the distinctive half moon–shaped scars left by an Aba-aba attack.
CONSERVATION STATUS
Not listed by the IUCN.
SIGNIFICANCE TO HUMANS
Very important food fish. Risk of overexploitation due to low reproductive capacity (low number of fry).
