AquaticRepublic.com - Synodontis irsacae (Mochokidae) All Fishes

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Close-up of head
Close-up of mouth showing teeth
Close-up of humeral process
S. tanganaicae above, S. irsacae below
Lateral view

All Fishes 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	According to Cuvier, Synodontis is an "ancient name for an undetermined fish from the Nile". It is not derived, as often reported, from syn-, together and odous, tooth, presumed etymology of the lizardfish genus Synodus and refers to the closely-spaced lower jaw teeth of both genera.
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 punctured by the sharp fin spines (which hurts - be careful). 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 fish's 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. It may also show a little redness if 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.
Habitat Information
Distribution	Africa: Lake Tanganyika. African Waters, Western Rift Valley Lakes, Tanganyika (click on these areas to find other species found there) Log in to view data on a map.
IUCN Red List Category	Not Evaluated
Husbandry Information
Feeding	Omnivorous, feeding on algae, sponges, ostracods, small crabs, insect larvae and fish eggs (Mathes 1959;Coulter1991a) User data.
Furniture	In Lake Tanganyika inhabits littoral to benthic zones over shell, sand and mud bottoms.
Breeding	Unreported.
Breeding Reports	There is no breeding report.
Further Information
Reference	Folia Scientifica Africae Centralis v. 5 (no. 4), pp 78.
Registered Keepers	There is no registered keeper.
Wishlists	Love this species? Click the heart to add it to your wish list. There is no wish to keep this species.
Spotters	Spotted this species somewhere? Click the binoculars! There are 5 records of this fish being seen, view them all.
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Last Update	2020 Oct 04 00:56 (species record created: 2002 Apr 12 00:00)