Growth, maturity, condition, size at sexual maturity and mortality of the Banded gourami Trichogaster fasciata from the Ganges River, Northwestern Bangladesh

The present study depicts the first comprehensive description on population structure, growth pattern (length-weight relationships, LWRs and length-length relationships, LLRs), condition factor (allometric, K_A; Fultonʹs, K_F; relative, K_R and relative weight, W_R), maturity (size at first sexual maturity; L_m), form factor (a_3.0) and natural mortality (M_w) of Trichogaster fasciata (Bloch and Schneider, 1801)in the Ganges River, Northwestern Bangladesh. In addition, asymptotic weight (W_α), a_3.0, L_m and M_w of this fish species from worldwide different water bodies were calculated based on the maximum total length. Samples of T. fasciata were collected from the fisher’s catch from August 2015 to July 2016 using cast net (mesh size ranges: 1.5 - 2.0 cm). For each individual, total length (TL) and body weight (BW) were measured using digital slide calipers and electronic balance with 0.01 cm and 0.01 g accuracy, respectively. A total of 278 individuals were analyzed, where the minimum and maximum TL were 3.3 cm and 9.9 cm, respectively and BW was 1.1 g and 22.04 g, correspondingly. The highest number (32.4%) of its population stands at 6.0 cm to 7.0 cm TL size group. The b value of LWR indicated negative allometric growth. Fulton′s condition factor (K_F) is the best condition and W_R showed significant dissimilarity from 100, signifying the balanced habitat for T. fasciata in the Ganges River. The a_3.0 was 0.0214, the L_m was 5.91 cm TL and M_w was 1.35 year^-1 of T. fasciata in the Ganges River. These findings will be very effective for its sustainable management in the Ganges River and connecting ecosystems.