Length-Weight Relationship and Condition Factor of Fourfinger Threadfin (Eleutheronema tetradactylum, Shaw 1804) in the Shibsa River Estuary, Bangladesh.

Abstract

The fourfinger threadfin, Eleutheronema tetradactylum (Shaw, 1804), is an economically important coastal fish species in Bangladesh, but information on its growth characteristics and body condition in the Shibsa River estuary remains limited. This study investigated the length-weight relationship (LWR) and condition factors of E. tetradactylum in the Shibsa River estuary, Bangladesh. A total of 100 individuals were collected from July 2022 to June 2023 with the assistance of local fishermen. Total length (TL) and body weight (BW) were recorded, and the length-weight relationship was estimated using the equation W=aLᵇ. Fulton’s condition factor (Kc), relative condition factor (Kn), and relative weight (Wr) were also calculated. The sampled fish ranged from 7.10 to 79.50 cm in TL and 2.17 to 3370.00 g in BW, with mean values of 20.25 ± 15.44 cm and 220.49 ± 570.84 g, respectively. The LWR showed a strong and significant relationship (BW=0.0057TL³·¹¹; R²=0.998, p<0.001), with a positive allometric growth pattern (b = 3.11). The mean Kc, Kn, and Wr were 0.73±0.08, 1.06±0.09, and 106.34±9.21, respectively. The predominance of smaller individuals in the sample and the Kn and Wr values above unity and 100, respectively, suggest relatively favorable body condition of the sampled fish. These findings provide baseline information on the growth characteristics and condition of E. tetradactylum in the Shibsa River estuary and may support future fisheries assessment and management of the species.