Abstract
For the very first time the sex ratio, length-weight relationships (LWRs), length-length relationships (LLRs), form factor, as well as condition factor were calculated for bartail flathead, Platycephalus indicus, captured with gill nets (mesh size: 2.0-6.0 cm) from the Bay of Bengal, Bangladesh, from August 2021 to January 2022. A digital caliper was used to measure the length to 0.1 cm accuracy, and an electronic balance was used to quantify weight to the accuracy of 0.01 g. The sex ratio for the sample was 1: 0.76 (Male: Female). The estimates of slope in the fitted linear regressions relating logarithms of weights to logarithms of the total, standard, and fork lengths varied from 2.978 to 3.297, and the coefficient of determination from 0.89 to 0.97. Moreover, the three-length measures were also strongly associated (r(2) > 0.996; P < 0.05). For the males, females, and combined sexes, the computed form factors were 0.0111, 0.0112, and 0.0107, correspondingly. For both males and females, individuals in the 33-36 cm and 27-30 cm length classes exhibited the highest and lowest in all the four condition factors, respectively. The size at first sexual maturity for combined sex of P. indicus was 30.2 cm in total length in the Bay of Bengal, Bangladesh. These results of the study will help with the conservation and long-term management of this species in the Bay of Bengal, Bangladesh, and other nearby nations.