Actinopterygii (ray-finned fishes) > Perciformes
(Perch-likes) > Cichlidae
(Cichlids) > Pseudocrenilabrinae
Etymology: Oreochromis: Latin, aurum = gold + Greek, chromis = a fish, perhaps a perch (Ref. 45335).
Oreochromis mossambicus bassamkhalafi is placed only under the genus Oreochromis in Eschmeyer (CofF ver. May 2011: Ref. 86870). It is treated here questionably a synonym of Oreochromis mossambicus.
Environment / Climate / Range
Freshwater; brackish; benthopelagic; amphidromous (Ref. 51243); depth range 1 - 12 m (Ref. 57895). Tropical; 17°C - 35°C (Ref. 3); 13°S - 35°S
Length at first maturity / Size / Weight / Age
Maturity: Lm 15.4, range 6 - 28 cm
Max length : 39.0 cm SL male/unsexed; (Ref. 21); common length : 35.0 cm TL male/unsexed; (Ref. 9987); max. published weight: 1.1 kg (Ref. 40637); max. reported age: 11 years (Ref. 164)
(total): 15 - 18;
soft rays: 7 - 12;
Vertebrae: 28 - 31. Diagnosis: snout long; forehead with relatively large scales, starting with 2 scales between the eyes followed by 9 scales up to the dorsal fin (Ref. 3058, 3060). Adult males develop a pointed, duckbill-like snout (Ref. 52307) due to enlarged jaws, often causing the upper profile to become concave (Ref. 2, 7248, 12524, 13337, 52307), but upper profile convex in smaller specimens (Ref. 1870, 6460). Pharyngeal teeth very fine, the dentigerous area with narrow lobes, the blade in adults longer than dentigerous area; 28-31 vertebrae; 3 anal spines; 14-20 lower gill-rakers; genital papilla of males simple or with a shallow distal notch; caudal fin not densely scaled; female and non-breeding male silvery with 2-5 mid-lateral blotches and some of a more dorsal series; breeding male black with white lower parts of head and red margins to dorsal and caudal fins (Ref. 2).
Africa: Lower Zambezi, Lower Shiré and coastal plains from Zambezi delta to Algoa Bay. Occurs southwards to the Brak River in the eastern Cape and in the Transvaal in the Limpopo system (Ref. 6465). Widely introduced for aquaculture, but escaped and established itself in the wild in many countries, often outcompeting local species (Ref. 12217). Several countries report adverse ecological impact after introduction.
Adults thrive in standing waters (Ref. 7248, 12501). Inhabit reservoirs, rivers, creeks, drains, swamps and tidal creeks; commonly over mud bottoms, often in well-vegetated areas (Ref. 44894). Also found in warm weedy pools of sluggish streams, canals, and ponds (Ref. 5723). Most common in blind estuaries and coastal lakes (Ref. 32693), but usually absent from permanently open estuaries and open sea (Ref. 6465) and from fast-flowing waters (Ref. 7248, 12501). Normally not found at high altitudes (Ref. 6465). Able to survive extreme reduction of temporary water bodies (Ref. 2, 27445). Highly euryhaline (Ref. 2, 3, 23, 58, 61, 6465, 12501, 12522, 12524, 13337, 27445, 55352). Grow and reproduce in fresh-, brackish and seawater (Ref. 2, 21, 23, 61, 5214, 27445, 36683, 54362). Can be reared under hyper-saline conditions (Ref. 4537, 44894, 52307). Tolerate low dissolved oxygen levels (Ref. 3, 23, 6465) and can utilise atmospheric oxygen when water oxygen levels drop (Ref. 61, 6465). Mainly diurnal. May form schools (Ref. 3, 4537, 44894). Omnivorous (Ref. 21, 12524), feed mainly on algae and phytoplankton (Ref. 4537, 7248, 12501, 12522, 12524, 13337, 36683, 44894, 52307) but also take some zooplankton, small insects and their larvae (Ref. 4537, 7248, 12524, 13337, 44894, 52307), shrimps (Ref. 12524, 13337), earthworms (Ref. 12501) and aquatic macrophytes (Ref. 6465). Juveniles carnivorous/omnivorous, adults tend to be herbivorous or detritus feeders (Ref. 2, 6465, 13517). Large individuals have been reported to prey on small fishes (Ref. 2, 6465, 12501, 12522), and occasionally cannibalise their own young (Ref. 2, 6465). Exhibit considerable plasticity in their feeding habits (Ref. 6465, 13544) as well as in their reproductive biology (Ref. 13544). Polygamous (Ref. 12524, 13337), maternal mouthbrooder (Ref. 1, 5214, 12524, 13337). Reach sexual maturity at 15 centimeter length (Ref. 44894), but stunted fish may breed at 6-7 centimeters and at an age of just over 2 months (Ref. 52307). Fecundity high (Ref. 55352). Extended temperature range 8-42 °C, natural temperature range 17-35°C (Ref. 3), with salinity-dependent difference in temperature tolerance (Ref. 2, 23). Somewhat aggressive toward other species (Ref. 36683). Marketed fresh and frozen (Ref. 9987). Excellent palatability (Ref. 6465), with small head and large dress-out weight (Ref. 61), and filets without small bones (Ref. 57960). Used extensively in biological, physiological and behavioural research (Ref. 7248). Translocated and introduced for aquaculture, sport fishing, stocking man-made lakes and biological control of nuisance plants and animals (Ref. 6465). Eurytopic; a most successful and vagile invader (Ref. 6465).
Spawns at the edge of the littoral terrace of lakes (Ref. 1, 2, 87, 6465), in sandy or muddy bottoms (Ref. 57425). Displays a lek mating system; territorial males establish breeding territories where they dig spawning pits, assume a dark coloration, defend a breeding territory and actively court females; sneaking males intrude into nests during a spawning episode, exhibiting quivering behavior which is usually an indicator of sperm release; sneaking is predominantly performed by subordinate males, which may adopt pseudo-female behavior (Ref. 57425). Only territorial males produce sounds, during all phases of courtship but especially during the late stages, including spawning (Ref. 49830). Territorial male excavates and defends a basin-shaped pit in the center of his territory, where female deposits 100-1700(1800) eggs (Ref. 44894, 52307). Eggs and milt are sucked up by the female (Ref. 2, 44894). Fertilization is reported to sometimes occur in the mouth of the female (Ref. 6028). Females incubate eggs alone (Ref. 12501, 52307). It is possible, albeit rare, that males take up some eggs after spawning (Ref. 2, 5726, 52307, 57895), but they almost always eat them soon after (Ref. 52307). Females school together while mouthbrooding (Ref. 40035), they cease to feed and subsist on food reserves stored in their body (Ref. 1). Females may spawn a full clutch with just one male, or may spawn with several different males in a series (Ref. 52307). Water is circulated over the eggs by chewing movements of the jaws (Ref. 12501, 12522). Fry hatch in the female's mouth after 3-5 days (Ref. 2, 12501, 12522, 44894, 52307), depending on the temperature (Ref. 52307). The young are released from the mouth in 10-14 days, but remain near the female and enter the mouth if threatened until about 3 weeks old (Ref. 2, 44894, 52307). Fry and juveniles shoal in shallow water (Ref. 6465, 7248, 57895) where they feed during the day, and retreat to deep water at night (Ref. 87, 6465). Females raise multiple broods during a season (Ref. 7248, 57895).
Trewavas, E., 1982. Tilapias: taxonomy and speciation. p. 3-13. In R.S.V. Pullin and R.H. Lowe-McConnell (eds.) The biology and culture of tilapias. ICLARM Conf. Proc. 7. (Ref. 1)
IUCN Red List Status (Ref. 96402)
CITES (Ref. 94142)
Threat to humans
Fisheries: highly commercial; aquaculture: commercial; gamefish: yes; aquarium: commercial
Estimates of some properties based on models
Phylogenetic diversity index (Ref. 82805
= 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.01820 (0.01431 - 0.02314), b=2.98 (2.94 - 3.02), based on LWR estimates for this species (Ref. 93245
Trophic Level (Ref. 69278
): 2.2 ±0.0 se; Based on diet studies.
Resilience (Ref. 69278
): Medium, minimum population doubling time 1.4 - 4.4 years (K=0.2-0.5; tm<1; tmax=11).
Vulnerability (Ref. 59153
): Low to moderate vulnerability (32 of 100) .