Length-weight relationship and condition factor of four Actinopterygii, Perciformes ray-finned fish species of India

Abstract Fish length-weight relationships, or LWR s, are an essential tool in fish biology that has gained an abundance of attention. The study reports the length-weight relationship and condition factor of four Teleostei, Perciformes ray-finned fish species of the Indian freshwater river Gomti, Lucknow (Uttar Pradesh). A total of 145 individuals of Parambassis ranga, Johnius coitor, Nandus nandus and Anabas testudineus were procured from April 2021 to May 2022. LWR s were expressed by linear regression models in P. ranga (Log W = -1.54 + 2.75 Log L), J. coitor (Log W = -1.89 + 2.92 Log L) , N. nandus (Log W = -1.73 + 2.98 Log L) and A. testudineus (Log W = -0.42 + 1.83 Log L). LWR s showed highly significant ( P <0.001) negative allometry (slope<3) for all the species. The slopes (b) estimated for P. ranga (2.75) and A. testudineus (1.83) are considered new records for the fish database. The minimum and maximum values of the coefficient of determination (R 2 ) recorded were 0.32 and 0.93 in A. testudineus and N. nandus, respectively, with a mean value of 0.724. Fulton’s condition factor (K) was above ‘1’ in P. ranga but less than ‘1’ in J. coitor, N. nandus and A. testudineus . In A. testudineus , both the slope ‘b’ and ‘K’ indicated stressed conditions, which reflect the depletion of energy reserves. The comparative account of the current growth pattern and health of a selected fish species provided by the present study will be considered to be helpful for the assessment of population dynamics and implementing sustainable conservation measures. Besides, the data generated for A. testudineus in the present study corresponds to the alarming conditions of the constricted species, which are desirable for proper management.