Breeding and Rearing of Regal Damselfish Neopomacentrus cyanomos (Bleeker, 1856): The Role of Green Water in Larval Survival

Abstract

Recent developments in the marine ornamental fish trade have drastically encroached on the coral ecosystem. To ensure the sustainable development of the aquarium industry, it is necessary to develo p hatchery technology for different marine ornamental organisms. In this context, we investigated the breeding success of regal damselfish, Neopomacentrus cyanomos, in low salinity water and studied the role of green water in larval survival. Since the regal damselfish is polygamous, an experiment on breeding group formation was made. We observed that it took groups of 2 fish 7.6 months to spawn, whereas groups of 6 fish bred in 3.3 months. Before spawning, males changed body colour on their dorsal side to attract a partner. In the rearing tanks, eggs were laid in an earthen pot and the male guarded the clutch until hatching, not allowing his female partner to enter the nesting area during this time. Hatching generally took place 4 days after fertilization but sometimes occurred on the fifth day. Larvae were reared using 2 experimental setups in order to examine the importance of green water to larval survival. The water quality, photoperiod and feed supplied were similar in both setups. However, in setup I, clear water was provided and in setup II green water was provided and the larval survival rate was 0% and 20% respectively. The larvae metamorphosed on day 35 post-hatching. The results presented here provide additional information about the importance of green water in damselfish larval rearing.