| Premnas Biaculeatus(Premna, Perciformes, Pomacentridae), Whoes common name is rosy clownfish and with the purple-brown body of the length of 10~15cm, They named after "clown" because there are one or two white stripes on its body, like a clown in the opera. They all widespread in the sea of south China, India Ocean and the western Pacific. Because of the beautiful appearance, they had been classified as ornamental fish. have a symbiotic relationship with sea anemones, and the clownfish have occupied an important position in the ornamental fish trade market.So far, the vast majority of marine ornamental fish are fished from the sea, and with the overfishing, the ecology of marine has been severely damaged, the number of clownfish has sharply dropped. The clownfish in Philippines and Hainan are on the verge of die out, then researchers of domestic and foreign study on the artificial propagation and large-scale of cultivating young fishes, they made some achievements. But there is few reports of different light temperature and salt influenced Premnas Biaculeatus’ s fertilized eggs. So we made a study of its fertilized eggs to observe the effects of temperature, light and salt on the embryonic development were discussed.Choosing the healthy body without injuries that were collected from India Ocean as the broodstock fish, After a successful pairing feeding in the aquarium which the water was recycled by a filtration syeterm, at the water temperature of 24℃, 26℃,28℃,30℃, analyze the record of spawning cycle, the incubation time and hatching, the result is that the most suitable temperatures are 26℃,28℃, Under the light 1000 lx, analyze the record of spawning cycle, the incubation time and hatching of the three group 10 h L:14h D,12 h L:12h D,14 h L:10h D, the result is that the most suitable light is14 h L:10h D.The development process of P.biaculeatus oosperm under the laboratory conditions of 26~27℃, salinity of(25±1) was studied. It was found that the oosperm of P.biaculestus was oval,The long diameter of oosperm was 1.99 mm. According to the morphlological characteristics, the embryonic development process was divided into 10 stages : percleavage atage, cleavage atage, blastula stage, gasturla stage, neurlua stage, somite stage, turnover stage, angiogenesis stage, organ formation stage and hatching stage; the color of oospermin in the development process was gradually deepened. the oosperm of P.biaculestus took about 154 h to complete the whole incubation period at water temperature of 26℃, the whole lengh of newly-hatched larvae was 3.6±0.1mm.The development process of P. biaculeatus oosperm under the laboratory conditions of(26±1)℃, the eggs were hatched in the water with nine salinities 0, 5, 10, 15, 20, 25, 30, 35, 40. The effects of salinity on hatching time, haching rate, survival rate of every stage, deformity rate. The result was that in the salinity 25,35,the hatching rate reached the highest level, they are(78.6±0.6)%,(82.0±0.2)%,the malformation rate reached its lowest level, they are 0.8%,1.0%(P<0.05). Salinity 30,35 has the shortest incubation time, it’s about 152 h, salinity 30,25 has the highest survival rate,83.4%, 73.7%. So the result is that embryonic development of suitable salinity is 25 to 30. |
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