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Siluriformes (Catfishes) >
Schilbeidae (Schilbid catfishes)
Etymology: intermedius: From the Latin «rostrum» (snout) and «depressus»
(flattened), referring to the dorsolateral flattened snout
of this species (Ref. 43912).
More on author: Rüppell.
Issue
Until recently, this species was known as Schilbe mystus, but De Vos and Skelton (1990) have shown, after morphological examination of the holotype of Silurus mystus Linnaeus, 1758, that this specimen belongs to the species generally known as Schilbe (Eutropius) niloticus (Rüppel, 1829); in accordance with the international code of zoological nomenclature, the older name, Schilbe mystus, should substitute the more recent name Schilbe niloticus; hence, the species erroneously considered to be Schilbe mystus, is now called Schilbe intermedius Rüppel, 1832, which is the oldest valid name (Ref. 57127).
Environment: milieu / climate zone / depth range / distribution range
Ecology
Freshwater; pelagic; potamodromous (Ref. 51243); depth range 0 - 60 m (Ref. 34291), usually 0 - 30 m (Ref. 34291). Tropical
Africa: Senegal, Gambia, Casamance, Corubal, Geba, Little Scarcies, Sassandra, Boubo, Bandama, Agnébi, Mé, Comoé, Tano, Pra, Volta basin, Mono, Sio, Ouémé, Ogun, entire Niger and Chad basins, Cross, Wouri and Sanaga; absent between Little Scarcies and Sassandra; further in the entire Congo River basin, Malagarasi, Luiche, Cunene, Okavango, entire Zambezi including the Kafue system, Lake Kariba, Nile, Lake Victoria basin, Webi Shebeli, Wando, Tana, Galana, Athi, Wami, Rufiji-Ruaha, Lake Rukwa, lower Sabi-Lundi, Shire below Murchison Falls, Lake Chilwa, Ruvu, Pungwe, Limpopo, Incomati and Pongola (Ref. 43912).
Length at first maturity / Size / Weight / Age
Maturity: Lm 10.0, range 11 - ? cm
Max length : 50.0 cm SL male/unsexed; (Ref. 57127); max. published weight: 1.4 kg (Ref. 43912)
Dorsal spines (total): 1; Dorsal soft rays (total): 5 - 6; Anal soft rays: 41 - 66. Diagnosis: 8-13 gill rakers (exceptionally 7-14, Ref. 43912) on lower limb of first gill arch; 41-66 branched anal-fin rays; eyes positioned laterally (Ref. 43912, 57127, 81643). In the Nile (Ref. 43912) and in West Africa adipose fin usually absent, but specimens with a rudimentary adipose fin occasionally present (Ref. 43912, 57127, 81643). In Central and East Africa populations without as well as with entirely developed adipose fin occur; in several populations both morphotypes are mixed together, the adipose fin being absent or present but sometimes varying in size from a recognizable protrusion low down the back to a fully developed adipose fin; posterior nostrils always closer to each other than are anterior ones; lower jaw reaches beyond snout but hardly remarkable in some specimens, mouth being almost isognath; inner side of pectoral spine feebly serrated; nasal barbel at least reaching to midway between eye and opercle but often reaching beyond this level; small specimens (up to about 15 cm) with typical colour pattern with dark lateral bands along sides and anal fin, this pattern gradually disappearsing in larger specimens, the body becoming in general entirely brownish, yellowish and silvery with very few traces of dark lateral bands (Ref. 43912). Eyes positioned laterally (Ref. 81643).
Reported to be a pelagic species (Ref. 34290), generally abundant in open water, in both lacustrine and fluviatile conditions, often showing shoaling habits; seems to prefer large or rather large rivers and lakes and apparently rarely penetrates small rivers or small affluents (Ref. 43912). Occur mainly on shallow waters. Migrate to the surface at night (Ref. 34291). Surface feeder; nocturnal, omnivorous, voracious and predaceous (Ref. 43912). Feeds on fish (juvenile as well as adults), insects (aquatic as well as terrestrial ones, larvae as well as adult insects), molluscs, freshwater prawns and other crustaceans, algae and bottom-living and planktonic organisms; vegetable material and eggs were also reported from stomach contents (Ref. 43912). Primarily piscivorous at 13-34 cm TL (Ref. 34291, 43912). Rarely grow to lengths greater than 30 cm SL (Ref. 34290). Maximum total length recorded 60.5 cm (Ref. 43912), 52331). Maximum lifetime observed almost 10 years (Ref. 43912). Spawn throughout the year peaking once (Ref. 34291). Migrate into rivers in fairly compact schools during the rainy season to spawn in floodwater pools (Ref. 34291). Reproduction occurs at high water after the floods (Ref. 43912). Oviparous, eggs are unguarded (Ref. 205). Flesh edible and of good flavour; possible aquaculture species (Ref. 43912).
Distinct pairing (Ref. 205).
De Vos, L., 2003. Schilbeidae. p. 97-116 In C. Lévêque, D. Paugy and G.G. Teugels (eds.) Faune des poissons d'eaux douce et saumâtres de l'Afrique de l'Ouest, Tome 2. Coll. Faune et Flore tropicales 40. Musée Royal de l'Afrique Centrale, Tervuren, Belgique, Museum National d'Histoire Naturalle, Paris, France and Institut de Recherche pour le Développement, Paris, France. 815 p. (Ref. 57127)
IUCN Red List Status (Ref. 130435)
Threat to humans
Harmless
Human uses
Fisheries: commercial; aquaculture: experimental
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Estimates based on models
Phylogenetic diversity index (Ref.
82804): PD
50 = 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00708 (0.00540 - 0.00927), b=3.06 (2.98 - 3.14), in cm total length, based on LWR estimates for this species (Ref.
93245).
Trophic level (Ref.
69278): 3.6 ±0.60 se; based on food items.
Resilience (Ref.
120179): Medium, minimum population doubling time 1.4 - 4.4 years (tmax=5, probably greater; K=0.1-0.3; Fec = 18,000).
Fishing Vulnerability (Ref.
59153): Low to moderate vulnerability (29 of 100).
Nutrients (Ref.
124155): Calcium = 109 [51, 259] mg/100g; Iron = 1.97 [0.87, 3.77] mg/100g; Protein = 17.2 [15.3, 19.0] %; Omega3 = 0.546 [0.197, 1.527] g/100g; Selenium = 68.2 [27.0, 172.9] μg/100g; VitaminA = 43 [15, 128] μg/100g; Zinc = 1.37 [0.90, 2.07] mg/100g (wet weight);
