Malakar et al.

and Moyle, 2000; Bonner and Wilde, 2002; Quist et al., 2003). Fish species

strongly depend on the characteristics water morphology and its dynamics.

Fishes are therefore good indicator of ecomorphological habitat conditions and

can be used in the environmental planning (Schiemer, 2000). In India, extensive

studies on freshwater fishes have been conducted in relation to either taxonomy

(Jayaram, 1981; Datta Munshi and Srivastava, 1988; Talwar and Jhingran, 1991;

Menon, 1992) or capture fisheries or aquaculture (Jhingran, 1975). Studies on fish

assemblage structure and their habitat requirements in Indian Rivers are scanty

though few initiatives have been taken in South Indian streams (Arunachalam et

al., 1988, 1997, 2000) and river of Ganges basin (Sarkar et al., 2007).

Ompok is an important genus of family Siluridae that retains four freshwater fish

species in India namely: O. bimaculatus (Indian butter catfish), widely distributed

in India and other countries of Southeast Asia; O. malabaricus, found in Western

Ghats of Kerala, Goa and Maharashtra; O. pabda (pabdah catfish), distribution

confined to Indus and Brahmaputra drainages; and O. pabo , mainly found in

Ganga and Brahmaputra River systems in North Bengal and Assam, respectively.

Because of a great morphological and wide distribution, these fishes are obviously

an attractive group for experimental and evolutionary biologist. The three Ompok

species viz. O. pabda, O. pabo and O. bimaculatus are highly priced delicious

catfishes and well preferred because of their relatively few bones. The natural

populations of these catfishes have been greatly declined in the tributaries of river

Ganga basin (Sarkar et al., 2008, 2010). Due to reduced abundance, these species

have been listed as threatened species as per IUCN criterion (CAMP, 1998;

CAFF, 2006; Lakra and Sarkar, 2006). Lack of definite information on the habitat

preference of these threatened Silurids in their distributional range has been

hindering species-specific conservation and management strategies. The study

aimed at identifying priority habitat of the three Silurids ( O. pabda, O. pabo and

O. bimaculatus ) in Tones, Gomti, Ganga, Bramhaputra and Hoogly rivers of India.

Materials and Methods

Samples Collection

The fish samples were collected from 40 selected sites as the representatives of

landscapes in all the studied rivers viz. Chak Ghat (River Tones), Lucknow (River

Gomti), Malda (River Ganga), Guwhati (River Bramhaputra) and Kolkata (River

Hoogly). Sampling were performed five times at each site covering premonsoon

(March–June), monsoon (July–August) and postmonsoon (September and

October) seasons from 2007 to 2010. The habitat data were analyzed from 318

individuals of Ompok species viz . O. pabda, O. pabo and O. bimaculatus. In each

of these sampling sites, fishing has been done at night (17 H to 7 H) and during

136

International Journal of Bioinformatics and Biological Sciences : v.2 n.3&4. Dec. 2014