Chitala lopis (Bleeker, 1851)
Species overview
A knife fish, growing to considerable size. Body only in specimens under 300 mm with numerous scattered irregular spots, in larger ones without any markings.
Size observed: up to 1.5 m, 20 - 30 kg.
Taxonomic description
- Body shape typically knife shaped, with strongly concave upper profile of the head, in particular in large specimens, less so in younger ones. Greatest depth as in other species of the genus above origin of anal fin, humpbacked.
-Underside of head convex; depth above opercular cleft in lare fish two times the depth above the eye.
-Mouth terminal, its edge far beyond posterior rim of eye.
-Preopercular scales same size as body scales.
-Opercular cleft long, round.
-Origin of pectoral fin above level of edge of mouth, in length this fin reaches slightly beyond origin of anal fin.
-Dorsal fin present, with short base.
-Anal fin very long, 117-127 fin-rays, merging without conspicuous border in caudal fin, 15 fin-rays, its longest fin-rays at about middle of the fin. 79-85 vertebrae.
As in other Chitala external characters of body other than colour not really suitable to identify the species.
-Coloration, ground coloration silvery, greyish or olivaceous to dark brown, flanks brighter, countershaded.
There are considerable changes in coloration dependend on age and body length. In young fish between 150 and 270 mm the entire body, including anal and caudal fin usually is covered with numerous small spots - maculosus-phase. Smaller specimens are not yet known. Over 30 cm SL all have a round black spot at the base of the pectoral fin, and most specimens between 30 and 60 cm have numerous small round dark spots on the body, mostly the anterior part; there also may be a few oblique wavy bars at the end of both body and anal fin - borneensis-phase. Specimens longer 60 cm only have the black spot at the base of the pectoral fin and no other marks, - hypselonotus phase.
Type locality
N. lopis : >Java, Batavia, Samarang, in fluviis e paludibus<,
N. borneensis, N. maculosus : >Sambas, in fluviis<,
N. hypselonotus : >Palembang, Sumatrae austro-orientalis, in flumine Mussi.<
Distribution
Borneo, Sumatra, Malay peninsula, Thailand, for details see Roberts (1992: 371).