Cat-eLog Right Arrow Mochokidae Right Arrow Mochokinae Right Arrow Synodontis

Jump to next section Cat-eLog Data Sheet
Scientific Name Synodontis irsacae  Matthes, 1959
Common Name
Type Locality Kalundu, northern Lake Tanganyika.
Pronunciation sin oh don tiss - er say see
Etymology Synodontis: From the Greek syn, meaning together, and odontos, meaning tooth; in reference to the closely-spaced lower jaw teeth. 
Jump to next section Species Information
Size 157mm or 6.2" SL. Find near, nearer or same sized spp.
Identification All species in the genus Synodontis have a hardened head cap that has attached a process (humeral process) which is situated behind the gill opening and pointed towards the posterior. The dorsal fin and pectoral fins have a hardened first ray which is serrated. Caudal fin is always forked. There is one pair of maxillary barbels, sometimes having membranes and occasionally branched. The two pairs of mandibular barbels are often branched and can have nodes attached. The cone-shaped teeth in the upper jaw are short. S-shaped and movable in the lower jaw. These fish produce audible sounds when disturbed rubbing the base of the pectoral spine against the pectoral girdle.

Body grayish to cuprous brown, lower body lighter. Scattered irregularly-shaped black spots on juvenile specimens, spots becoming slightly smaller in large specimens. Maxillary and mandibular barbels white, bases sometimes with scattered dusky pigmentation. Iris copper colored. Dorsal and pectoral –fin spines dark, terminating in short, light to dusky colored filaments. Anterior margin and ventral side of pectoral fin light colored. All rayed fins with black triangles at their base. Both lobes of caudal fin black, posterior margin white. Axillary pore absent; mandibular teeth 15-29; 8-9 pectoral-fin rays; premaxillary toothpad interrupted; Maxillary barbel with distinct basel membrane; secondary branches on medial mandibular barbels present; skin of body smooth. Adipose fin long well developed, margin convex. Humeral process narrow, elongated, granulous, weakly developed ridge on ventral margin, dorsal margin concave, terminating in rounded point.
Sexing First lay the fish in your hand with its head toward your palm and the tail toward your fingers. Hold the dorsal spine between your middle and ring finger so the fish is belly up and you won't get stuck (Which by the way, hurts like crazy!). The genital pore is in a small furrow of tissue (in healthy fish) and will be obstructed by the pelvic fins. Pull down on the tail gently to arch the fishes spine and the pelvic fins will stand and the furrow open to display the genital pore and the anus of the fish. The male has a somewhat ridged genital papillae on which the spermatoduct is on the back side, facing the tail fin. A gravid female will also show an extended papillae but the oviduct is on the ventral side of the papillae (And may also show a little redness if really gravid). A thin or emaciated female will have just two pink pores, the oviduct and the anus.
General Remarks An explanation as to why Synodontis irsacae has often been called S. dhonti in the past. Synodontis dhonti (Boulenger 1917) was described from a single specimen collected in 1912. Synodontis irsacae (Matthes, 1959) was placed in junior synonymy with S. dhonti by Matthes in 1962 with specimens of S. irsacae being thought to be juvenile individuals of S. dhonti.
Wright & Page in 2006 put forth that none of these specimens have carried on any ontogenetic changes that would support the idea of S. irsacae being a juvenile form of S. dhonti. Mathes also cited a specimen n 1962 as being intermediate between the two species and this fish turned out to actually be a specimen of S. tanganaicae. Major differences separating S.irsacae from S. dhontibeing the absence of an axillary pore, retaining its spots and a smaller adult size.
Jump to next section Habitat Information
Distribution Lake Tanganyika, common and widely distributed.
African Waters, Western Rift Valley Lakes, Tanganyika (click on these areas to find other species found there)

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Jump to next section Husbandry Information
Feeding Omnivorous, feeding on algae, sponges, ostracods, small crabs, insect larvae and fish eggs (Mathes 1959;Coulter1991a)
Furniture In Lake Tanganyika inhabits littoral to benthic zones over shell, sand and mud bottoms.
Breeding Unreported
Breeding Reports There is no breeding report.
Jump to next section Further Information
References Wright, JJ and LM Page (2006) Taxonomic revision of Lake Taganyikan Synodontis (Siluriformes: Mochokidae). Florida Mus. Nat. Hist. Bull. 46(4):99-154.
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Last Update 2013 Jan 31 09:21 (species record created: 2002 Apr 12 00:00)