Life-history traits of Guntea loach, Lepidocephalichthys guntea (Hamilton, 1822) in the Payra River, southern Bangladesh

The present study provides the first wide-ranging elucidation of life-history traits, including length–frequency distribution (LFD), length–weight and length–length relationship (LWR and LLR), form factor (a_3.0), best condition factor (allometric, K_A; Fulton, K_F; relative, K_R; and relative weight, W_R), length at first maturity (L_m), natural mortality (M_w) and optimum catchable length (L_opt) of Lepidocephalichthyes guntea from the Payra River in southern Bangladesh. A total of 470 fishes were randomly collected seasonally from February 2019 to January 2020, using several traditional fishing gears (cast nets; drag nets; lift nets; and gill nets). The total length (TL), standard length (SL) and total body weight (BW) of each individual fish were measured with a 0.01 cm and 0.01 g precision, respectively. The TL size classes of 6.00–6.99 cm and 7.00–7.99 cm TL were the numerically dominant groups among the total fish population. Exponential b values of LWR (TL vs. BW) indicate a positive allometric growth (b = 3.20) pattern in the Payra River. The b value of LLR also indicates the same growth pattern. The estimated a_3.0 value was 0.007, indicating the fish has an elongated body profile. Among the four types of condition factors, K_F is the best-suited tool for evaluating the well-being of L. guntea in the Payra River. Additionally, W_R exhibited very significant divergence from 100 (p < .0001), designating an imbalanced habitat for L. guntea. The calculated L_m, M_w and L_opt values were 6.54 (~6.5 cm) in TL, 1.16/year and 7.46 cm TL for L. guntea in the Payra River, respectively. Thus, the results of the present study could be used in the future for improved management of this species in Payra River, as well as for linking ecosystems.