Oreochromis placidus (Trewavas, 1941)
Black tilapia
photo by Gratwicke, B.

Family:  Cichlidae (Cichlids), subfamily: Pseudocrenilabrinae
Max. size:  35.5 cm TL (male/unsexed); max.weight: 1,100.0 g
Environment:  benthopelagic; freshwater; brackish
Distribution:  Africa: Lower Zambezi and southwards in the lower parts of the Sabi, Lundi, Pungwe and Buzi Rivers (Ref. 5166); also Ruvuma River on the Tanzanian-Mozambique border; Lake Rutumba, Lupululu system, and the Lupuledi west of Lindi (Ref. 5166). Previously, two subspecies were recognized: Oreochromis placidus placidus and Oreohromis placidus ruvumae.
Diagnosis:  Dorsal spines (total): 16-18; Dorsal soft rays (total): 10-13; Anal spines: 3-4; Anal soft rays: 8-11; Vertebrae: 29-31. Description: Deep bodied with straight predorsal profile, mature males with concave profile, extended soft dorsal and anal fins (Ref. 52193). Gill rakers on lower limb of first gill arch 16-20 (Ref. 2, 52193). Dorsal fin with 16-18 spines and 10-13 soft rays; anal fin with 3-4 spines and 8-11 soft rays (Ref. 2, 52193). Lateral line scales 30-32 (Ref. 52193).

Colouration: Adults olive brown above, silvery below, with sooty grey head and fins; red margin to dorsal fin (Ref. 52193). Juveniles silvery with 8-9 faint vertical bars; soft dorsal, anal and caudal fins with dark streaks and light spots (Ref. 52193). Breeding males are very dark grey on head and body with throat and all fins black; with a red or orange margin on the dorsal and grey or black marblings on the gill-cover (Ref. 2, 52193).

Biology:  Prefers quiet pools with marginal vegetation; it has been reported only from fresh water and low altitudes and latitudes, so that its salinity and temperature tolerances are probably narrower than those of O. mossambicus (Ref. 2).
IUCN Red List Status: Least Concern (LC); Date assessed: 01 May 2018 Ref. (130435)
Threat to humans:  harmless


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