African mudfish

Phractolaemus ansorgii

FAMILY

Kneriidae

TAXONOMY

Phractolaemus ansorgei Boulenger, 1901, Niger delta. Species of the genus Phractolaemus have traditionally been placed within their own family, Phractolaemidae, but according to current research, they are closely related to kneriids and have been placed in Kneriidae by Grande and Poyato-Ariza.

OTHER COMMON NAMES

English: Hingemouth, snake mudhead; German: Afrikanischer Schlammfisch.

PHYSICAL CHARACTERISTICS

Standard length 6 in (15 cm). Elongate, cylindrical body with large cycloid scales. Head is small, broad, and strongly ossified; eyes are small and laterally positioned. Infraorbital bones two, three, and four are greatly enlarged. The mouth is highly projectile and capable of being thrust forward; at rest the mouth folds over into a depression on the upper surface of the snout. The mouth has no teeth except for a conical tooth on each dentry near the symphysis. There is a single narial opening preceded by a barbel. The opercular openings are narrow due to a sealing of the opercular boarder to the body wall. The interopercle is spinelike, and the preopercles are greatly enlarged, overlapping along the ventral midline of the body. There are six pelvic fin rays, six dorsal rays, and six anal fin rays. Three slender branchiostegal rays are evident. Unlike other gonorynchiform fishes, the swim bladder is divided into alveoli, which enables the fish to breathe atmospheric air. Body is uniformly gray above, light brown on the sides, pale ventrally with darkly colored fins.

DISTRIBUTION

Tropical Africa ranging through the lower Niger drainage and central Zaire basin.

HABITAT

Quiet, low-oxygenated muddy waters.

BEHAVIOR

Little is known about the behavior of this species. Unlike other gonorynchiforms, it is able to breathe atmospheric air, an ability that has made this fish of interest to aquarists.

FEEDING ECOLOGY AND DIET

Feeds on small, mud-dwelling organisms. Based on the presence of a moderately developed epibranchial organ, some researchers believe this species is an epiphytic feeder.

REPRODUCTIVE BIOLOGY

Utilizes external fertilization. Exhibits clear sexual dimorphism, as males sport conspicuous whitish breeding tubercles on the head, along the lateral line, and on the caudal peduncle.

CONSERVATION STATUS

Not listed by the IUCN. However, continued habitat destruction will undoubtedly affect the population dynamics and future of this fish.

SIGNIFICANCE TO HUMANS

Not an economically important food fish, but has been imported into the United States as an aquarium fish.