Tylochromis mylodon Regan, 1920
Mweru hump-backed bream

Family:  Cichlidae (Cichlids), subfamily: Pseudocrenilabrinae
Max. size:  22 cm SL (male/unsexed); max.weight: 963.9 g
Environment:  benthopelagic; freshwater
Distribution:  Africa: Lufira, Lake Mweru and the lower and middle Luapula (upper Congo River basin) in Democratic Republic of the Congo and Zambia (Ref. 52346).
Diagnosis:  Dorsal spines (total): 13-14; Dorsal soft rays (total): 14-15; Anal spines: 3-3; Anal soft rays: 7-8; Vertebrae: 28-28. Diagnosis: lateral line count of 38-43 scales; 16-17 closely packed gill-rakers along lower limb of first arch; extremely robust lower pharyngeal jaw with mill-like molariform teeth occupying at least 2/3 of dentigerous surface; third pore of mandibular laterosensory canal enlarged compared to size of preceding pores (Ref. 52346). Description: deep bodied (Ref. 52307, 52346) and robust (Ref. 52346). Predorsal head profile rises steeply (Ref. 52307, 52346) at an angle of about 55-60° over snout to orbit where a fleshy interorbital bulge is usually developed (Ref. 52346). From orbit to origin of dorsal fin, head profile frequently slightly more steeply inclined, lending typical hump-backed appearance; greatest depth along body at origin of dorsal fin; from nape to caudal peduncle dorsum strongly recurved, although body is more or less flattened along ventrum; mouth usually a little oblique when closed; lips well developed but not noticeably fleshy or thickened; mouth frequently agape and asymmetrically twisted; lower pharyngeal jaw extremely robust (Ref. 52346). Maxillary not extending to below eye; 3 series of scales on cheek (Ref. 52971). 16-17 closely packed gill-rakers along lower limb of first arch; 3-4 elongate and simple hypobranchial rakers, remaining ceratobranchial rakers crenate and overlapping; epibranchial rakers rather broad and frequently bifurcate; vertebral apophysis well developed and robust, and of the standard Tylochromis type (Ref. 52346). 40-41 scales in longitudinal series; 7 scales between dorsal spine and lateral line; 27-29 scales in upper lateral line; 34-35 scales in lower lateral line; 2 scales between upper and lower lateral line (Ref. 52971). Upper branch of lateral line terminates well in advance of end of dorsal fin, usually about level of 7th-8th soft ray from free end; terminal canal bearing scales do not descend scale rows; dorsal and ventral branches of lateral line on caudal fin extend almost to fin periphery, and median branch often absent, but when present usually reaches only about halfway onto fin; dorsal fin spines increase rapidly to the fifth and then are more or less equal in length; anal fin rounded; pectoral fins extremely long and reaching middle of soft anal fin; first pelvic ray frequently produced but rarely reaches beyond level of vent; caudal fin strongly emarginate, but only finely scaled in dorsal and ventral fields (Ref. 52346). Coloration: no details about living coloration known (Ref. 52307, 52346). Preserved juveniles often silvery with dusky grey snout and interorbital region, a dusky brown dorsal fin with numerous non-ocellate white spots, a small indistinct opercular blotch and a well marked nape-stripe, and 5-6 well developed vertical bars which extend down onto flanks to below midline; vertical barring less distinct and often entirely lacking in preserved adults; in large males longitudinal striations are associated with each scale row, particularly marked on caudal peduncle and dorsum; longitudinal striations only faintly evident in females; males with black upper lip and striking creamy white upper lip membrane, lower lip and gular region; in both sexes dark grey/brown dorsal fin membrane marked with numerous rows of small white non-ocellate spots, as is anal fin in males; male caudal fin striped and spotted in a typical manner (Ref. 52346).
Biology:  Benthic macrophage (Ref. 52346). Feeds mainly on insects and their larvae, but also (in small quantities) on crustaceans and molluscs (Ref. 52307). Maternal mouthbrooder (Ref. 52307, 52346) that does not pair bond (Ref. 52307). Marked intolerance to oxygen lack (Ref. 246).
IUCN Red List Status: Least Concern (LC); Date assessed: 16 February 2009 Ref. (130435)
Threat to humans:  harmless


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