Meristic and morphometric characteristics relationships, condition factor and breeding biology of Indian potashi (Neotropius atherinoides) in the Adjacent River of Chalon Beel, Bangladesh

Neotropius atherinoides locally known as Batasi fish and considered as freshwater small indigenous species (SIS) in Bangladesh. The present study describes the first complete, inclusive description of length-weight relationships (LWRs), length-length relationships (LLRs), condition factors (Fulton’s, KF; Relative, KR) and the breeding biology in the adjacent river of Chalon beel, Bangladesh. The total number of fin rays was counted using a magnifying glass and different lengths were measured using digital slide calipers with 0.01 cm precision. Bodyweight (BW) was measured by a digital balance to the nearest 0.01 g accuracy, respectively. From the present study few mean differences are observed in fin formula: Dorsal, D. 1/3-6; Pectoral, Pc. 1/4-7; Pelvic, Pv. 3-7; Anal, A. 30-45; and Caudal, C. 16-20. The linear relationship observed in length-length relationships (LLRs) and the value of LLRs (r≥0.94) indicated that they were highly correlated. While in length-weight relationships equation (W= aLb), calculated b values (b>3.00) indicating positive allometric growth with a high correlation coefficient (r) in combined sexes. Condition factor value (K>1.0) indicating habitat (Cholon beel) was still in good condition. The maximum mean GSI value was found in the month of April (21.34±4.87) indicating April was the spawning season of the species. Breeding parameters gave better relationships when compared to GSI, fecundity with body weight and standard length. These parameters are essential for evaluating the relative condition of fish and sustainable management as well as their fisheries and species identification.