Embryonic development of the striped spiny eel, Mastacembelus pancalus (Hamilton, 1822) in captive condition

[摘要] The striped spiny eel, Mastacembalus pancalus is one of the common food fish in Bangladesh, but lacking study on embryonic development of the fish. The present study describes the embryonic progress stages of the fish in the confined state. The embryogenesis is divided into seven major phases: Zygote phase, Cleavage phase, Morula phase, Blastula phase, Gastrula phase, Organogenesis phase and Hatching phase. According to distinct development characteristics, the further sub-stages were also developed whenever possible. Fertilized eggs were sticky, colorless, and demersal with identical perivitelline space. The thickness of the unfertilized eggs ranged from 0.55-0.58 mm, which increased to 0.62-0.71 mm in fertilized eggs. The perivitelline space development happened at 0.35 h after fertilization (AF). The first cleavage groove occurred at the animal pole (two cells) 0.55 h AF. The added cell division such as four cells, eight cells, sixteen cells, thirty-two cells, and multi cells stages was initiated at 1.25, 1.45, 2.15, 2.50, and 4.40 h AF respectively. The morula, blastula, gastrula, yolk plug stage, and organogenesis stages were seen at 8.25, 11.30, 17.15-23.50, 29.20, and 34.15-35.30 h AF respectively. The initial heartbeat was observed at 34.00 h AF. The head and tail ends of the embryo were distinguished at 35.00 h AF. The notochord was also evident at the same hours. The embryo started to hatch at 36.00 h AF which accomplished 39.00 h at 29.11 ± 0.29 °C. The new hatchling was 1.65 ± 0.15 mm in average length. The present findings will serve as baseline information to develop the breeding protocol of the species in the hatchery condition.

[学科分类] 生物科学（综合）

[关键词] Embryogenesis;cleavage;organogenesis;hatching