Preliminary Study On Artificial Breeding Of Small Marine Angelfish

Marine angelfish are important members of marine aquarium fish.They have colorful skin and beautiful body shape.Most of them inhabit in the coral reef ecosystem.In recent years,due to the deterioration of coral reef ecosystems and destructive fishing methods,wild resources have been decreasing,while the market prices rised continuosly.Artificial breeding has become a hot issue.In present study,the small marine angelfish represented by the genus Centropyge was selected,and the introduction,domestication and mating of broodstock were studied to obtain broodstock with continuous spawning.The appearance differences between male and female fish of the Centropyge broodstock,the mating behavior and spawning status,and the development of the embryo and early larvae stage were further observed.The effects of temperature,light and water flow on the embryonic development were studied.The first bait of the larvae also was investigated.The main results are as follows:1)Fish from East Africa and the United States are easier to domesticate and paired than that of from other places,and most of the paired fish need 2-3 month for conditioning before ready to spawn while the fasted pair spawned within one month post successful pairing.The main reason for the above differences is that the methods used for collecting and transporting the Centropyge fish in different places or fish with different prices are very different,resulting in great differences in the body status and the ability to adapt to the new environment and artificial bait.In addition,highly adaptable species such as Centropyge flavicauda are relatively easy to domesticate.2)Sex transformation is ubiquitous in Centropyge.Most species have no obvious appearances difference between male and female fish,but they are obviously different in size.In the pairing process,if one large and one small sub-mature fish are selected,tthen the probability of success pairing is high.The Centropyge with different life habits showed similar countship behavour,but the demand for living space is quite different.C.flavicauda and the C.acanthops which with smaller body size spawn and fertilized normally in the tank provided by present study,the number of eggs produced daily is stable at > 400,and the fertilization rate is over 80%.However,although C.loricula can spawn in a short time after successfully pairing,the fertilization rate is low.One possible reason is the male fish might not mature enough,another reason may be related to the breeding space is too small to spawn.3)The embryonic development and post-embryonic development of the Centropyge is basically same.They are all telolecithal eggs with a single oil droplet,disc-shaped cleavage,embryo development including cleavage stage,blastocyst stage,gastrula stage,neuroblast stage and organ formation stage.The embryo could be hatched after 19 hours post fertilization at water temperature of 23-24.5?,.4)Temperature and light have a significant effect on the embryonic development of the Centropyge.Temperature mainly affects the embryonic period;light can cause certain damage to embryo and lead to a decline of hatching rate.The water flow caused by micro-inflation has no significant effect on embryo hatching,but very weak water flow can cause damage to newly hatched larvae.Washing eggs with ultraviolet-irradiated salt water is beneficial to the embryo hatching and laval fish development.5)From the newly hatched larvae to the 3dph larvae,they all relying on the yolk in the yolk sac to provide nutrition.their eyes and digestive tract have not yet fully developed,and they could not to open mouth and intake the food.Generally,3 dph larvae can be intake food and showed no obvious selectivity for diferent food at the beginning,but the feeding appetitre gradually decreases with development,leading to malnutrition death before the first metamorphosis.