Siluridae

Abstract: Ompok argestes, a new species of silurid catfish, is described from the southwestern lowlands of Sri Lanka. The new species is distinguished from all other species of Ompok in the Indian subcontinent by a combination of the following characters: body color pattern mottled; predorsal profile uniformly convex; maxillary barbels reach or extend slightly beyond base of dorsal fin; eye diameter 14.2–17.1% head length (HL); body depth at anus 19.8–22.3% standard length (SL); head width 14.3–16.8% SL; caudal peduncle depth 5.6–6.5% SL. Callichrous ceylonensis Gunther is shown to be a valid species that is apparently restricted to Sri Lanka, distinguished by a combination of the following characters: distinct concavity in predorsal profile; origin of pelvic fin beneath or slightly posterior to the origin of the dorsal fin; maxillary barbels 108–166 % HL; mandibular barbels 16.1–33.7 % HL; and 58–66 anal-fin rays.

Abstract: Among siluroid fishes (catfishes), the Malapteruridae uniquely possess an electrogenic organ. Although much attention has been paid to the anatomy and physiology of the electric organ, little emphasis has been given to other anatomical characters, particularly with regard to their indicating phylogenetic relationships. Ten character complexes involving cranial bones, muscles, swimbladder connections and vertebral column are here analysed and compared with those of other siluroids. It is concluded that despite its obvious specializations (autapomorphies) the Malapteruridae is basically a plesiomorphic group and that its relationships lie with some taxa belonging to the Old-World Siluridae. The Siluridae are thus a paraphyletic assemblage, with other included taxa having their close relationships with the Schilbeidae. The evolutionary potential for development of the electric organ is accounted for by the loss of a rigid connection between the pectoral girdle and the skull and the associated modification of...

Abstract: Summary The present study describes the condition factor, length-weight and length-length relationships for an endangered freshwater fish species Ompok pabda (Hamilton) of the family Siluridae from the River Gomti in Northern India. The values of regression parameter b ranged from 2.81 to 3.32 (r2 > 0.90). During the pre-monsoon, the allometric coefficient b of the LWR was close to isometric value (b = 3.08) allometric (b = 2.87), although it suggested negative allometric growth in monsoon periods while positive growth in post-monsoon. The condition factor values ranged from 0.672 to 0.744. Results of the present study could be useful to help in conservation and sustainable fisheries management of this endangered species.