Reproductive Biology of Flying barb, Darkina, Esomus danricus with some related characteristics

摘要

The aim of this study was to evaluate the biology of a small fish, darkina, Esomus danricus collected from natural pond located in the Fisheries Field Laboratory complex, BAU, Mymensingh. The experiment was undertaken in a pond using thirty six small hapas (0.25 m 3 ) and one big hapa (1 m 3 ). All the hapas were placed in a big pond (420 m 2 ). The stocking density was 10 sp./hapa and 40 sp./hapa in small (H s ) and big hapa (H b ), respectively. The fishes of three small hapas out of thirty six were emptied and measured with their length (cm) and weight (g) in each month. But the fishes of big hapa were counted and weighed in every month and released in that hapa up to the end. No supplementary feeding was applied for darkina. This experiment was continued from May’13 to April’14. The key biological characteristics i.e. gonado-somatic index (GSI), condition factor (K) and four polygon of ova diameter were given an indication the breeding season extended from June to October. Fecundity and gonad weight was positive correlation which was expressed as the equation, Y= 5705.x + 1926 (R 2 =0.605). Furthermore, to get increased or decreased number of fishes could presumably the spawning period. Within the suitable physico-chemical parameters, monthly morpho-histological examination of the gonad disclosed the existence of five maturity stages (immature, maturing, mature, ripe and spent & resting) in darkina. Both the male and female were represented more or less similarly breeding periodicity. Considering microscopic and histological assessment of fishes occur the peak breeding in June & September. The experimental fish was also established to be a manifold spawner. The knowledge of key characteristics would be useful to impose adequate regulation for the conservation and proper management of the species.