Oreochromis lidole (Trewavas, 1941)
Oreochromis lidole
photo by FAO

Family:  Cichlidae (Cichlids), subfamily: Pseudocrenilabrinae
Max. size:  38 cm SL (male/unsexed)
Environment:  benthopelagic; freshwater; depth range 30 - 100 m,
Distribution:  Africa: Lake Malawi (Ref. 2, 5166, 118630). Reports from Lake Chungruru (Ref. 2, 54852) and Lake Kingiri (Ref. 2, 54852) are misidentifications of Oreochromis chungruruensis and juvenile Oreochromis squamipinnis respectively (Ref. 118638).
Diagnosis:  Dorsal spines (total): 14-17; Dorsal soft rays (total): 10-11; Anal spines: 3-3; Anal soft rays: 8-10; Vertebrae: 30-32. Diagnosis: breeding male black; length of head 34.4-42.4% SL; length of lower jaw 31.3-40.0% head length (Ref. 2). Teeth of jaw in 3-4, rarely 5 rows (Ref. 2,6150). Lower pharyngeal bone with restricted toothed area; median length of bone 33.0-40.7 % length of head and 1.3-1.5 times its own width; blade 1.9-3.9 times median length of toothed area (Ref. 2). Description: lower outline of body flat (Ref. 2781). Deepest part of body generally in front of anterior end of dorsal fin (Ref. 2781, 52161, 55427). Head large (Ref. 2781, 4967, 6150, 55079). Relative size of head increases with growth (Ref. 2). Jaws large (Ref. 2781, 55079). Small jaw teeth (Ref. 2) in narrow bands (Ref. 2, 2781, 4967). Reduced dentition, 3-5 regular rows of teeth (Ref. 55079). 2-3 series of scales on cheek, occasionally a few small scales of a 4th row (Ref. 54852). Lower pharyngeal bone long-bladed (Ref. 55079), slender (Ref. 6150), with concave sides (Ref. 2781, 52161, 55427), supporting a small toothed area (Ref. 2781, 6150, 54852, 55079) with very fine teeth (Ref. 54852). Scaly coating of caudal fin rarely obscuring outlines of rays (Ref. 55427). Coloration: ripe male black (Ref. 2, 87, 2781, 4967, 6150, 40193) with white margin to dorsal (Ref. 2, 2781) and often also caudal and anal fins (Ref. 2). Males lose their black coloration in a few seconds on being alarmed, turning a pale grey, often with iridescent greenish or coppery areas on the flanks or head (Ref. 40193). Non-breeding fishes are silver-grey to fawn-grey, darker on the dorsum, with black vertical bars of uneven length from the dorsum to mid-flanks, but these may be dimmed (Ref. 2). Small specimens and females with 5 dark blotches, vertically drawn out, along the side and some with 2 fainter on the caudal peduncle; vaguer markings in a more dorsal row; females without marginal dorsal band; caudal fin clear in small specimens (Ref. 54852). Juveniles are shallow-bodied with a flat belly, possess a Tilapia-mark which is often dumbell-shaped and usually surrounded with yellow pigment, and have a blue sheen and fairly definite vertical black stripes on the body (Ref. 2781).
Biology:  Occurs in all kinds of habitats but is mainly found in open water away from the coast (Ref. 5595). The most pelagic of the Lake Malawi Oreochromis species (Ref. 2, 87, 4364, 4916, 4967). Forms schools (Ref. 2, 2781). Feeds on phytoplankton (Ref. 2, 87, 5595, 10402, 42295, 52161). Female mouthbrooder (Ref. 2). It is suspected that Oreochromis lidole is now globally extinct, as it has not been positively recorded since 2007 (Ref. 118638).
IUCN Red List Status: Critically Endangered (CR); Date assessed: 20 June 2018 (A2d) Ref. (130435)
Threat to humans:  harmless

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