Mastacembelus nigromarginatus Boulenger, 1898
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Family:  Mastacembelidae (Spiny eels)
Max. size:  42.2 cm SL (male/unsexed)
Environment:  benthopelagic, potamodromous
Distribution:  Africa: coastal river basins from the Cess/NipouĂ© as western distribution border and certainly up to the Volta and questionably up to the Niger River basin as eastern distribution border (Ref. 57415).
Diagnosis:  Dorsal spines (total): 28-32; Dorsal soft rays (total): 82-104; Anal soft rays: 75-94; Vertebrae: 91-98. Diagnosis: no pre-opercular spines; 27+1 up to 31+1 (median 29+1) dorsal spines; distance from anterior border of snout to last externally visible dorsal spine 49.7-57.6% SL (m=54.2), increasing with size; distance from posterior edge of pectoral fin to anterior origin of 1st dorsal spine between (-21.7) and 0.0% HL [m = -11.8]; pre-orbital spine as good as always present; snout with a more pointed appearance; origin of 1st dorsal spine situated anterior to, or below, posterior edge of pectoral fin; distance from anterior border of snout to last externally visible dorsal spine 50.0-57.6% SL (m=54.1), shorter than distance from anterior border of snout to last externally visible anal spine, 54.2-62% SL (m=58.3), both decreasing in percentages with increasing size; post-anal length 43.5-51.0% SL (m=46.3) increasing with size, shorter than pre-anal length, 48.3-55.1% SL (m=52.5) and decreasing with size, becoming equal to latter with increasing size; 9-12 caudal fin rays; 4-6 predorsal vertebrae; 35-40 abdominal vertebrae; (+4)-(+5) in-between vertebrae; 53-60 caudal vertebrae (Ref. 57415). Coloration: light brown overall background colour; lateral sides characterized by a more or less pronounced dark brown battlement pattern, which forms a well delimited edge between dark lateral sides and lighter colour dorsal sides and dorsal midline; nevertheless, dorsal midline often with a series of dark brown saddle-like blotches; ventral side of head, belly and abdomen white, yellowish of colour but not so well delimited from lower sides; lower sides with irregularly shaped, white, yellowish spots; background colour of dorsal caudal and anal fins white, transparent, mottled scarcely with small, round, brown spots; dorsal and anal fin base with a series of dark brown, round spots partially situated, respectively, on dorsal and ventral part of tail; often those spots not independent but connected with dark brown-coloured tail and can even be interpreted as an enlargement of tail colour pattern on basal part of fins; on the more distal part of dorsal and anal fins additional small dark brown spots can be observed; pectoral fins white, yellowish of overall background colour with small light brown spots and a brown base; colour pattern changes with size, especially darkening of unpaired fins; nevertheless, outermost margin of dorsal, caudal and anal fins always remains white; in addition, small dark brown spots situated on more distal part of median fins, gradually with increasing size, form a continuous broad, black band on these fins; on anal fin this band is often connected with ventral side of tail due to an enlargement of the spots situated on base of fin resulting in a series of yellowish, white spots on base of anal fin; on dorsal fin both remain separate; upper edge of lateral dark brown band with its battlement pattern becomes less contrasted or may even disappear (Ref. 57415).
Biology:  Maximum reported TL was 443mm (Ref. 57415).
IUCN Red List Status: Least Concern (LC); Date assessed: 30 April 2006 Ref. (123251)
Threat to humans:  harmless
Country info:   

Entered by: Sa-a, Pascualita - 09.05.94
Modified by: Musschoot, Tobias - 27.05.15
Checked by: Sa-a, Pascualita - 12.07.94

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