| Family: |
Dorosomatidae (Gizzard shads and sardinellas) |
| Max. size: |
17 cm SL (male/unsexed); max.weight: 40.0 g |
| Environment: |
pelagic; freshwater; depth range 10 - 60 m, non-migratory |
| Distribution: |
Africa: endemic to Lake Tanganyika (Ref. 188, 28136, 107916), but introduced into several other lakes, like Lake Kivu, Lake Kariba and Cahora Bassa reservoir (Ref. 188, 7248, 28136, 52193, 107916). Also reported as Microthrissa stappersii from Lake Mweru (Ref. 246, 52958), but this is based on an erroneous type locality of the species (Ref. 26733). |
| Diagnosis: |
Dorsal spines (total): 0-0; Dorsal soft rays (total): 13-18; Anal spines: 0-0; Anal soft rays: 15-19; Vertebrae: 41-44. Diagnosis: Body fairly slender, depth about 22-24% of standard length; pre-pelvic scutes not strongly keeled, beginning behind base of last pectoral fin ray; maxilla blade over 4 times as long as its shaft, its lower toothed edge continued forward to meet hind tip of pre-maxilla; second supra-maxilla asymmetrical, lower half larger; lower gillrakers long and slender, 35-40; a distinct silver stripe along flank (Ref. 188, 1878). Its synonym Limnothrissa stappersii is characterised by fewer lower gill rakers, 22-25, fewer anal fin rays, 15-17, and the absence of scutes, and represents possibly a juvenile form of L. miodon (Ref. 188, 26733). It resembles Stolothrissa tanganicae of Lake Tanganyika, which is more slender, has a small eye and a shorter maxilla blade not reaching forward to hind tip of premaxilla (Ref. 188).
Description: Body torpedo-shaped with short fins, pectorals low on body, pelvics behind dorsal origin, anal long-based, caudal forked (Ref. 7248, 52193). Mouth terminal; lower jaw projecting, lower front teeth large, sharply pointed and curved backward; upper jaw without median notch (Ref. 188, 7248, 52193). Gillrakers long and slender, closely set, 35-40 on lower part of anterior arch; number of lower gill rakers 20-25 for Limnothrissa stappersii, which is possibly a juvenile form of L. miodon (Ref. 188, 1878, 26733). Dorsal fin with 13-18 rays, equally distant from centre or posterior border of eye and from root of caudal, longest rays about half length of head; anal fin with 15-19 rays, a long way behind the dorsal, nearer to root of caudal fin than to base of pelvic fins; pectoral fin 3/5 length of head, widely separated from pelvic fin; pelvic fin inserted below anterior third or middle of dorsal, with 1 unbranched and 7 branched rays; caudal fin deeply forked, with pointed lobes (Ref. 188, 1878, 26733, 52193, 93833). Scales small and thin, easily shed; 45-48 scales in longitudinal series; 14 transverse scales (Ref. 1878, 52193). With 11-15 prepelvic and 6-11 postpelvic scutes, with pre-pelvic scutes not strongly keeled and beginning behind base of last pectoral fin ray (Ref. 188, 7248, 26733, 52193). Total number of vertebrae 41-44 (Ref. 26733).
Colouration: Olive above; silvery below, with a blue indistinct lateral band; dorsal and caudal greyish, other fins white (Ref. 1872, 1878). |
| Biology: |
Inhabits offshore areas of lake Tanganyika; also occurs at rivermouths, where the water is not too muddy and not very different physico-chemically from the Lake (Ref. 5393); lacustrine, forming large schools (Ref. 188, 7248), preferring open water (Ref. 13337). It has been successfully introduced to Lake Kivu, Lake Kariba and Cahora Bassa reservoir (Ref. 4967); found throughout Lake Kariba in both inshore habitats and open water to a depth of 20-35 m depending on the thermocline (Ref. 7248, 52193). Feeds on plankton, especially atyid shrimps, also copepods and prawns, but larger individuals apparently take larval Stolothrissa (Ref. 188). Cannibalism does occur (Ref. 13337). Breeds close to the shore throughout the rainy seasons, but with peaks in May/June and December/January (Ref. 188). Fire is used to attract the fish and caught by means of scoop nets (Ref. 36900). Used widely as bait by anglers, especially for tigerfish (Ref. 7248, 52193). |
| IUCN Red List Status: |
Least Concern (LC); Date assessed: 31 January 2006 Ref. (130435)
|
| Threat to humans: |
potential pest |
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