Optimization of temperature improves embryonic development and hatching efficiency of false clown fish, Amphiprion ocellaris Cuvier, 1830 under captive condition

The false clown fish, Amphiprion ocellaris is a promising candidate species in the global marine aquarium trade. The lack of sustainable hatchery production and the over-exploitation from the wild cause severe threats to their natural population. Environmental factors influence the survival and existence of aquatic animals, and the temperature is one of the most crucial factors determining survival, especially during the early embryonic developmental stages. The present study evaluated the effect of temperature on embryonic development by exposing the fertilized eggs to varying temperature (26 °C, 27 °C, 28 °C, 29 °C, and 30 °C). Temperature significantly (P < 0.05) affected the duration of embryonic phases. The incubation period varied significantly (P < 0.05) among different temperatures, resulting in reduced incubation period at higher temperatures (29 °C and 30 °C) compared to the lower temperatures (26 °C, 27 °C and 28 °C). Similarly, higher hatching efficiency coincided with eggs incubated at 29 °C and 30 °C (29 °C – 95.61 ± 2.41% and 30 °C – 98.05 ± 1.37%) while the lowest hatching efficiency was noticed at 26 °C (63.77 ± 2.95%). Higher incubation temperature (30 °C) featured a markedly decreased yolk volume (0.162 ± 0.02 mm³), whereas lower temperatures (26 °C, 27 °C and 28 °C) had significantly higher yolk volume at hatching. Although 30 °C resulted in better hatching efficiency, it negatively affected the yolk volume at hatching. While comparing the combined effect of temperature on hatching efficiency and yolk volume, the present study recommends 29 °C as the optimal temperature for proper embryonic development and larval survival. This study indicates that the optimization of water temperature is an effective way to accelerate embryonic development and hatching efficiency to increase production cycles of A.ocellaris for sustainable ornamental fish culture.