Length–Weight, Length–Length Relationships and Condition Factor of Labeo bata from Five Different Districts of Bangladesh

Abstract

The study describes the length–weight relationship, length–length relationship, and condition factor (CF) of Labeo bata. The species is a well-known and widely distributed Indian minor carp found throughout Bangladesh. However, due to habitat destruction and environmental obstacles, the fish is at risk of extinction, and the IUCN has recently listed it in the Red List category. Therefore, studying the biology and physical condition of the species is essential for its conservation and management. Thirty specimens from each population were collected from five different districts of Bangladesh, namely Chuadanga, Jhenidah, Chandpur, Barisal, and Mymensingh. Total length (TL), fork length (FL), and standard length (SL) were measured using a measuring scale in centimetres, while body weight (BW) was measured using a digital balance. Data were analyzed using Microsoft Excel and SPSS 16.0 software. The study revealed that the body weights of all populations were positively correlated with TL, SL, and FL. However, the relationships were strongly correlated for the Chuadanga and Chandpur populations. The reported relationships included Chuadanga BW = 7.747SL − 58.62 (r² = 0.783), Chuadanga BW = 5.694FL − 55.28 (r² = 0.837), Chandpur BW = 7.346SL − 57.60 (r² = 0.706), and Chandpur BW = 7.195FL − 67.12 (r² = 0.764). The remaining length–weight relationships were reported as moderately or weakly correlated. The study also revealed that the length–length relationships were positively correlated. Strong relationships were reported for Chuadanga FL = 1.139TL + 0.558 (r² = 0.894), Chuadanga SL = 1.340TL − 0.341 (r² = 0.907), Jhenidah FL = 0.793TL + 0.616 (r² = 0.852), Jhenidah SL = 0.782TL − 0.158 (r² = 0.834), and Mymensingh SL = 0.619TL + 5.189 (r² = 0.845). All other relationships were moderately or weakly correlated. The b values for the populations of Mymensingh, Chuadanga, and Barisal districts indicated positive allometric growth patterns, with values of 4.713, 5.694, and 5.936 (b > 3.0), respectively, for the body weight–total length relationship. In contrast, the populations of Jhenidah and Chandpur had b values of −0.850 and 2.834 (b < 3.0), respectively. The relationships among the populations were not found to be very strong, indicating that the growth patterns were not satisfactory in relation to their environmental and other physical parameters. The condition factors (CF) of all populations were lower than the standard value of 3.0. The highest condition factor was recorded for the Jhenidah population (1.67 ± 0.51), while the lowest was recorded for the Mymensingh population (0.84 ± 0.16). The condition factors indicated that the physical well-being of the species, with respect to environmental conditions and food availability, was not optimal. This suggests that the fish is at risk throughout the country. The study recommends that necessary steps should be taken to improve the physiological and ecological conditions of Labeo bata to ensure higher growth rates and better survival.