Mystus gulio is a commercially important estuarine small catfish in Bangladesh and it is prone to decreasing due to natural and anthropogenic changes. Information of induced breeding of this catfish and its embryonic development could contribute to database and conservation approach. The S-GnRHa dose optimization and embryonic-larval development study were conducted in a freshwater condition in order specify optimal dose of synthetic hormones in induced breeding. The synthetic GnRHa was used as induction agent where male injected half of the doses of female and a control without S-GnRHa was assigned. The stages of embryonic development were observed under a photomicroscope. Average fertilization and hatching rates varied from 74.33% to 83.89% and from 72.33% to 85.11% respectively among different treatments and control females did not ovulate. The eggs of M. gulio was firmly adhesive and immediately after spawning the average diameter of fertilized eggs were 0.48±0.01 mm. After fertilization, the first cleavage stage of M. gulio occurred within 40 min. The distinctiveness of blastomeres was progressively dropped and morula, blastula, and gastrula stages were found at 3:40 h, 4:20 h and 5:00 h, respectively after fertilization. The larvae-initiated hatching at around 21:00 h after fertilization and total length of larvae were computed 1.11±0.01 mm while the temperature of water was 30±1°C. The present study revealed that application of S-GnRHa hormone at dose of 0.5 ml kg-1 body weight of female could be efficacious for production of M. gulio seed in freshwater successfully.
Novelty Statement | This research work is very first approach to breed Mystus gulio by using S-GnRHa in freshwater environment and to observe their early development stages.
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