Heterogeneity in habitat use of three threatened freshwater catfishes (Siluridae: Siluriformes) in five major tropical rivers of India

To identify the priority habitats of the threatened catfishes of the genus Ompok viz. Ompok pabda, O. pabo and O. bimaculatus in India the effects of habitat variables on the structure of fish assemblage were evaluated from 40 sampling sites located in Tones, Gomti, Ganga, Bramhaputra and Hoogly Rivers. Canonical correspondence analyses were carried out to determine the influence of environmental conditions on species occurrences and assemblage characteristics. The microhabitat, hydromorphological parameters (depth and current velocity) followed by conductivity, temperature and total dissolve solid (TDS) were found to be significant in structuring the assemblage of the three catfishes. Fast water with shallow depth in different rivers was significantly associated with occurrence of O. pabda whereas slow water and higher depth were significantly associated with O. bimaculatus. Some other environmental parameters such as conductivity, TDS and pH were also found to be significant in shaping the habitat preference of the Ompok species studied. Our results depicted the importance of environment influences on the Ompok species which are of conservation and management interest.