Threatened fishes of the world: Horabagrus brachysoma (Gunther, 1864) (Bagridae)

Common names: Gunther’s catfish, Yellow catfish. Vernacular: Manjeletta, Manjakoori. Conservation status: Endangered (Molur & Walker 2001). Identification: Described by Gunther (1864) as Pseudobagrus brachysoma placed into Horabagrus (Jayaram 1955). The only other species in the genus is Horabagrus nigricollaris. This species has a moderately elongated, compressed body with a large head and a wide sub-terminal mouth. Eyes are large, inferior, and visible in ventral profile. Dorsal with 5 – 7 rays and a large anterior spine; Pectoral fins with 8 – 9 rays and a large anterior spine serrated along its posterior edge with large antrorse teeth; adipose separated from dorsal fin by a broad gap; pelvic fins with six rays; anal fin long, 23 – 29 rays. Four pairs of barbels; 1 nasal 2 mandibular and 1 maxillary. Caudal fin forked or deeply emarginated. Lateral line complete and simple. Key character: A black ocellus extending from the humeral region of each side over the nape, bordered by light yellow ring. Distribution: Restricted to rivers (and occasionally lakes) in the southern region of the Indian subcontinent. Known from the Chalakudy, Periyar, Meenachil, Manimala, Pampa, Moovatupuzha, Achenkovil rivers and Vembanad Lake in the State of Kerala and Aghanashini and Kali rivers of Karnataka State. Abundance: Previously abundant in the rivers of Kerala, but have declined precipitously (60 – 70%) during the last few years (Molur & Walker 2001). Habitat and ecology: Benthic, primarily occupying lowland areas of rivers and backwaters with mud and sand substrate, but has also been recorded from the deep pools in hill streams. They are seen in high abundance at the beginning of southwest monsoon (June–August) and subsequently occur in lower profusion after the monsoon season. Reproduction: Spawning occurs during the pre-monsoon months and finishes by the southwest monsoon. Size at sexual maturity of the female fish is 21.5 cm and the fecundity varied between 1500 and 21,184 (Kurian & Inasu 2003). Threats: H. brachysoma is imperiled by the alteration of riverine habitats, aquatic pollution, and exploitation for food and ornamental purposes. Conservation action: National Bureau of Fish Genetic Resources and Regional Agricultural Research Station of the Kerala Agricultural University have conducted experimental trials on captive breeding of this species. The Kerala State Council for Science, Technology and Environment has granted a major research project to the Department of Zoology, University of Kerala to study the life history traits, captive breeding and culture of H. brachysoma. Conservation recommendations: Suitable sanctuaries for this species should be created in selected areas of the rivers. Surveys to determine the current status of wild populations are of highest priority. Since H. brachysoma is one of the most important food and ornamental species exploited in the inland waters of Kerala, this yellow catfish embodies the problems that must be resolved for sustainable management of the riverine fishery of this region. The species could be hence considered as a potential ‘‘flagship species’’, which can be used to increase the environmental profile of inland biodiversity, facilitate proper media attention and provide a focus for conservation action (Prasad et al. 2005). Remarks: H. brachysoma has aquaculture potential in both the food and ornamental trades. It is already established on the international market as a highly desired ornamental fish.