Reproductive biology of an endangered catfish, Ompok bimaculatus (Bloch, 1794) in the lotic waterbodies of Tripura, North-East India

Abstract

The reproductive biological characteristics of Ompok bimaculatus, an endangered catfish of commercial importance were observed. 436 fish samples were collected from different lotic water bodies of Tripura between 2008 and 2011. Total weight of the sampled fish varied from 22 to 171.50 g and length varied from 16.50 to 33.0 cm. Dominance of female over male was observed in the species. The ratio of male to female was 1:1.65. Significant correlation was exist between fish length and weight in both males (R²=0.943) and females (R²=0.827). The regression parameter ‘b’ was close to 3.084 during summer, showing that fishes were growing isometrically in relation to length. However, value of ‘b’ during monsoon (b=2.851) and winter (b=2.192) were indicating allometric growth. The condition factor (K) in the females was found to be varied from 0.423 to 0.637 while, in males K value was ranged from 0.279 to 0.514. Monthly variation of maturity stages indicated the spawning period from May to August. Length at first maturity of female and male was 17.0 cm and 16.5 cm respectively. Maximum average Gonado-Somatic Index (GSI) values obtained for male and female were 2.195 and 15.582 respectively during spawning period and declined to minimum in October to January. The ova diameter was ranged from 0.827 to 1.358 mm. The fecundity was varied from 151-257 eggs/g body weight of fish which was highest during May to July. Linear relationship of fecundity with total length and body weight of the fish was found. The present findings divulge significant information on reproductive traits which can be further used for species restoration and captive breeding.