Actinopterygii (ray-finned fishes) > Gonorynchiformes
(Milkfish) > Phractolaemidae
Etymology: Phractolaemus: Greek, phraktos = fence + Greek, laimos = throttle (Ref. 45335); ansorgii: Named for the presence of 1-3 spines on the scales of the lateral line on the caudal peduncle, and on the 2 scale rows above and below the lateral line series (Ref. 93266). More on author: Boulenger.
Environment: milieu / climate zone / depth range / distribution range
Freshwater; benthopelagic; pH range: 6.0 - 8.0; dH range: ? - 25. Tropical; 25°C - 30°C (Ref. 13371)
Africa: in West Africa from Lake Nokoué (Ouémé River, Benin) (Ref. 81277) to Cross River (Cameroon) (Ref. 52397) including the Ogun, Osse and Niger Delta (Ref. 81277). Also in the middle Congo River basin (Ref. 93183) in Republic of Congo and Democratic Republic of the Congo.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 25.0 cm TL male/unsexed; (Ref. 93183)
Morphology | Morphometrics
soft rays: 6;
Vertebrae: 34 - 38. Diagnosis: head depressed and strongly ossified; anterior nostril elongate, forming an oblique, forward-pointing tube; posterior nostril crescent-shaped, located just behind the narial tube (Ref. 2913, 81277). Mouth small, protrusible (Ref. 245, 31256, 81277), placed at tip of a proboscis and opening upwards between the narial tubes (Ref. 2913, 81277), on upper surface of snout (Ref. 245, 31256). Narrow gill opening, but opercles very well developed, covering also the underside of the head where they overlap (Ref. 2913, 81277, 93183).
Lives in forest pools and swamps (Ref. 41580). Microphagous (Ref. 4910, 41580, 45483), especially phytophagous (epiphytes), and detritiphagous (Ref. 41580). Swim bladder entirely alveolar, functioning like a lung; this adaptation to aerial breathing allows the fish to survive under poor oxygenation conditions (Ref. 2913, 81277); recorded from nearly deoxygenated lungfish nest in Pool Malebo, Congo DR (Ref. 41585). Gonads, which are largely fused, are situated ventrally, not dorsally, in abdominal cavity (Ref. 41580). Mouth can be projected as a small trunk (Ref. 2913). Eggs transparent, yellow-greenish, 1.5-1.7mm diameter; large females may have several thousands of eggs (Ref. 41580). Particular blood system, with dark coloured and an abundant amouth of blood (Ref. 4910).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Males and females have lateral tubercles on their body which probably aid in maintaining contact during spawning (Ref. 38266).
Lévêque, C., 1990. Phractolaemidae. p. 189-191. In C. Lévêque, D. Paugy and G.G. Teugels (eds.) Faune des poissons d'eaux douces et saumâtres d'Afrique de l'Ouest. Tome I. Coll. Faune Tropicale n° XXVIII. Musée Royal de l'Afrique Centrale, Tervuren, and O.R.S.T.O.M.,Paris, 384 p. (Ref. 2913)
IUCN Red List Status (Ref. 120744)
CITES (Ref. 118484)
Threat to humans
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates based on models
Phylogenetic diversity index (Ref. 82805
= 1.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00437 (0.00168 - 0.01136), b=3.14 (2.91 - 3.37), in cm Total Length, based on LWR estimates for this (Sub)family-body shape (Ref. 93245
Trophic Level (Ref. 69278
): 2.3 ±0.1 se; Based on diet studies.
Vulnerability (Ref. 59153
): Low vulnerability (13 of 100) .