Biological and Reproductive Indices of Mystus bleekeri (Day, 1877) in Open Water Body (Dekhar Haor) of Bangladesh

Some biological and reproductive aspects of the Mystus bleekeri from Dekhar Haor were investigated. From the commercial catches, a total of 600 sample collections were performed on a monthly basis from July 2017 to June 2018. Total length (TL, cm), body weight (W, g) and individual’s sex were identified between 216 male (36%) and 384 female (64%) fish (ratio 1.00: 1.78). Mean TL and W of samples were 14.85±3.38 cm and 27.54±15.76 g, respectively. The TL of male and female ranged from 6.9-21.3 and 7.80-24.60 cm, respectively; and W ranged from 5.3-63.3 and 6.70-76.40 g, respectively. In length–weight relationship of this fish depicted a negative allometric growth (b=2.408) with a condition factor (Kn) of 1.04±0.11. Fish of 16.00-16.90 and 10.00-10.90 cm length groups demonstrated the highest (1.45±0.23) and lowest (0.89±0.18) Kn values, respectively which was significantly varied among different length groups. Monthly study of gonadosomatic index showed two peaks in the month of May-June and November for both sexes. The results of this study provide baseline data on some biological aspects of M. bleekeri, which would be useful in predicting the responses of M. bleekeri populations in Dekhar Haor.