SOME BIOLOGICAL ASPECTS OF THREE ENDANGERED FISH: Barilius bendelisis, B. barna AND B. tileo FROM THE ATRAI RIVER, DINAJPUR, BANGLADESH

Abstract

The present research was undertaken to estimate the length-weight relationship, condition factors and food habits of Barilius bendelisis, Barilius barna and Barilius tileo. Samples were collected monthly from Atrai river for six months from November 2015 to April 2016. Monthly relationships between total length (TL) and body weight (BW) as well as determination of growth pattern was performed for Barilius bendelisis, B. barna and B. tileo separately. Among 243 individuals B. bendelisis were 57, B. barna were 102 and B. tileo were 84. The total length and body weight of B. bendelisis ranged from 7 to 15.6 cm and from 3.55 to 34.1 g respectively. The total length and body weight of B. barna ranged from 4.9 to 7.9 cm and from 1.2 to 5.25 g respectively. The total length and body weight of B. telio ranged from 6.2 to 10.8 cm and from 2.61 to 11.94 g respectively. For B. bendelisis the generalized relationship of pooled data over the study period was BW = 0.020TL2.77. The study revealed high values of coefficient of determination in all months (r2 ≥ 0.869). At 95% confidence limits the „b‟ value revealed that the growth in January was isometric, and the growth in other months were allometric. B. bendelisis exhibited a higher condition factors (K) value (1.245±0.084) in February, 2016 and a lower K value (1.182±0.053) in April, 2016. For B. barna the generalized relationship of pooled data over the study period was BW = 0.017TL2.76. The study revealed high values of coefficient of determination in all months (r2 ≥ 0.820). At 95% confidence limits the „b‟ value revealed that the growth in January and April were isometric, and the growth in other months were allometric. B. barna exhibited a higher K value (1.201±0.110) in February, 2016 and a lower K value (1.110±0.226) in January, 2016. For B. tileo the generalized relationship of pooled data over the study period was BW= 0.026TL2.62. The study revealed high values of coefficient of determination in all months (r2 ≥ 0.833). At 95% confidence limits the „b‟ value revealed that the growth in January was isometric, and the growth in other months were allometric. B. tileo exhibited a higher K value (1.258±0.249) in February, 2016 and a lower K value (1.089±0.164) in April, 2016. The higher and lower mean RLG ± standard deviation (S.D.) of B. bendelisis in April and December were 2.01 ± 0.21 and 1.57 ± 0.17, respectively. The higher and lower mean RLG ± standard deviation (S.D.) of B. barna in November and January were 1.93±0.123 and 1.01±0.012, respectively. The higher and lower mean RLG±standard deviation (S.D.) of B. tileo in April and November were 1.78±0.21 and 1.25±0.180, respectively. Finally it was concluded that they are omnivore feeder. The present findings of length-weight relationship, condition factors and food habits of Barilius spp. in Atrai river might be used in future analyses of other population parameters and stock assessment of these valuable small indigenous species in Bangladesh.