Length-weight relationship, relative condition factor and morphological studies of Arius arius (Hamilton, 1822) in Hooghly-Matlah estuary, West Bengal

The present study deals with the length-weight relationship, relative condition factor, and morphometric and meristic characters of Threadfin sea catfish, Arius arius (Hamilton, 1822) from Hooghly-Matlah estuarine system, West Bengal, India. A total of 391 samples (243 females and 148 males) with the size ranging from 52 to 254 mm total length (TL) and weight ranging from 1.62 to 176.75 g were analyzed for a period of one year (April 2017 to March 2018). The ‘b’ value was estimated as 3.065, 3.127, and 3.104 for male, female, and pooled samples, respectively exhibiting positive allometric growth. The monthly mean relative condition factor (Kn) values ranged from 0.923 to 1.309 for males and 1.003 to 1.085 for females, respectively showing the good condition of the species. Fourteen morphometric characters analyzed revealed that the total length exhibited a highly significant correlation (p < 0.05) with most of the morphometric parameters. The analysis of meristic characters of A. arius found that the first dorsal fin bears 1 spine and 7 soft rays, pelvic fin is with 6 soft rays, pectoral fin bear 1 spine and 8-11 soft rays, anal fin bears 14-17 soft fin rays and the caudal fin is with 16-23 soft rays