Oreochromis variabilis (Boulenger, 1906)

Victoria tilapia
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Oreochromis variabilis
Male picture by Loiselle, P.V.

Classification / Names Populärnamn | synonymer | Catalog of Fishes (gen., sp.) | ITIS | CoL | WoRMS | Cloffa

Actinopterygii (strålfeniga fiskar) > Perciformes (Perch-likes) > Cichlidae (Cichlids) > Pseudocrenilabrinae
Etymology: Oreochromis: Latin, aurum = gold + Greek, chromis = a fish, perhaps a perch (Ref. 45335).

Environment: milieu / climate zone / depth range / distribution range Ekologi

; sötvatten bentopelagisk; djupintervall 4 - 49 m.   Tropical; 23°C - 28°C (Ref. 3)

Utbredning Länder | FAO områden | Ekosystem | Förekomster | Point map | Utplanteringar | Faunafri

Africa: Lake Victoria and its affluent rivers (Ref. 5166, 34290, 118630, 118638), Victoria Nile above Murchison Falls (Ref. 5166) and Lakes Kyoga, Kwania and Salisbury (Ref. 5166), but strongly declining or disappeared in many areas (Ref. 52331), apparently replaced by Oreochromis niloticus (Ref. 34290). Introduced into several dams in Lake Victoria region (Ref. 118638).

Size / Vikt / Age

Maturity: Lm ?  range ? - ? cm
Max length : 30.0 cm SL hane/ej könsbestämd; (Ref. 34290)

Short description Morfologi | Morfometri

Taggstrålar i ryggfenan (totalt): 16 - 18; Mjukstrålar i ryggfenan (totalt): 10-12; Taggstrålar i analfenan 3; Mjukstrålar i analfenan: 9 - 11; Ryggkotor: 29 - 31. Diagnosis: Large bodied tilapiine cichlid; females and unripe males have a grey/green body and fins with 6-7 dark vertical bars on the flank; ripening males with yellowish chin, and notable bright red/orange margins to the dorsal and caudal fins; fully ripe males are black with a blue sheen on the head, bright red/orange margins to the dorsal and caudal fins and a long, branched whitish or yellow genital tassel (Ref. 118638). The breeding male of Oreochromis variabilis is distinguished from O. niloticus and O. esculentus by the intense orange to scarlet colour of the margin of the dorsal fin and the long, tasselled genital papilla, as well as by the general body colour; the orange dorsal margin is present also in grown females and non-breeding males, though narrower and less brilliant (Ref. 2). Other distinguishing characters are: the tilapia-mark is absent in young longer than 15 mm standard length, whereas in O. esculentus it is conspicuous and with a clear ring up to about 70 mm standard length and may still be detected up to 170 mm; the profile usually has a convexity immediately before the eye; there are usually two rows of scales on the cheek in contrast to usually three in O. esculentus; in half-grown and full-grown fishes there are 4-7 series of teeth in the jaws, 3-5 in O. esculentus; the ratio depth of preorbital to length of head is more than 1/5 in O. variabilis, 1/5 or less in O. esculentus; longer gill-rakers; and whereas O. esculentus does not mount beyond the estuaries, O. variabilis enters rivers from the lake (Ref. 2). Oreochromis variabilis differs from both O. malagarasi and O. upembae, its nearest relatives, in the suppression in most phases of blotches on the flanks, in the body colour of mature males, which is blue-grey to blue-black vs. yellowish in O. upembae, in the shape of the profile, which in O. malagarasi and O. upembae lacks the 'bump' before the eye, a lower modal number of soft dorsal and anal rays, and a higher modal number of vertebrae; Oreochromis upembae also differs from O. variabilis in having usually narrow vertical stripes on the caudal fin (Ref. 2).

Biologi     Ordlista (t.ex. epibenthic)

Adults feed predominantly on bottom algae, some of the planktonic organisms that are found in their stomachs are probably those which have settled on the bottom or were washed shorewards from open waters but they do feed directly on plankton (Ref. 2). A maternal mouthbrooder, males make complex courtship structures in the substrate (Ref. 118638). Was a major component of the fisheries catch in Lake Victoria (Ref. 118638). Some pond culture attempted (Ref. 118638). IUCN conservation status is critically endangered (Ref. 118638).

Life cycle and mating behavior Könsmognad | Reproduktion | Lek | Ägg | Fecundity | Larver

Nests are built on sandy bottoms in shallow waters. Each nest consists of a central shallow saucer 13-15 cm in diameter, around which is a circle of small pits. This structure is the center of a larger pit, 30-39 cm in diameter. Breeding pair makes the T-stand. Female lays batches of eggs; picks them up and sucks at the male's genital tassel.

Main reference Upload your references | referenser | Koordinator : Kullander, Sven O. | Medarbetare

Trewavas, E., 1983. Tilapiine fishes of the genera Sarotherodon, Oreochromis and Danakilia. British Mus. Nat. Hist., London, UK. 583 p. (Ref. 2)

IUCN Red List Status (Ref. 119314)

  Critically Endangered (CR) (B1ab(i,ii,iii,iv,v)); Date assessed: 31 January 2006

CITES (Ref. 115941)

Not Evaluated

CMS (Ref. 116361)

Not Evaluated

Threat to humans

  Harmless





Human uses

Fiskeri: kommersiell; Vattenbruk: experimentell; Akvarium: Kommersiell
FAO(Publication : search) | FishSource |

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Estimates of some properties based on models

Phylogenetic diversity index (Ref. 82805):  PD50 = 0.5000   [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.01585 (0.00707 - 0.03555), b=2.98 (2.81 - 3.15), in cm Total Length, based on LWR estimates for this Genus-body shape (Ref. 93245).
Trofisk nivå (Ref. 69278):  2.0   ±0.00 se; Based on food items.
Resiliens (Ref. 69278):  Mellan, lägsta populationsfördubblingstid 1,4-4,4 år (Fec=500).
Vulnerability (Ref. 59153):  Low vulnerability (18 of 100) .
Price category (Ref. 80766):   Unknown.