Skeletal Ontogeny And Malformation Of Golden Pompano Trachinotus Ovatus Larvae

Golden pompano Trachinotus ovatus belongs to the family of Carangidae and is widely cultured in the Asia-Pacific region. Although the life cycle of golden pompano has been closed, and several key aspects relating to the larval rearing have been successfully explored. However, high malformations and low survival rate during its early stage have severely deferred the production efficiency and profitability of golden pompano aquaculture. As the first step to explore the formation of skeleton deformities, the normal vertebral column and caudal skeleton of larval golden pompano were investigated in this study, and skeleton deformities were recorded and analyzed up to 31 day-post-haching(DPH).(1) This work presents the first reference on the skeletal structure and their appearance during ontogenetic development in golden pompano from 1 to 31 DPH.Basicly, the ontogeny of skeleton was from 1-18 DPH. Meckel’s cartilage was visible on 3 DPH, and ossification of jaw was completed on 11 DPH. The vertebral column was mineralized from 7-9 DPH, and mineralization of vertebral column, including caudal vertebraes, was finished until 18 DPH. Caudal complex in golden pompano consists of three epurals(Ep), five hypurals(Hy), one parhypural(Phy), a neural spine(Ns) and two haemal spines(Hs). Over 33% of the experimental fish exhibited at least one type of malformation. This part of study has explored the osteological ontogeny of golden pompano, and identified the type, presenting time and frequency of skeletal malformations.(2) The effect of temperature on the rearing performance and malformation of golden pompano larvae was investigated. The water temperature of 26-29 o C favored growth and survival, but 23 o C was too low for both. Jaw, vertebral column and caudal vertebra deformity significantly increased at 33 o C. Therefore, the temperature range of 26 – 29 o C is optimal, and temperature >33 o C and <23 o C may have adverse impacts on fish performance.(4) The effects of nutritional enhancement on the rearing performance and boney malformation of larval golden pompano was examined during the Artemia naupliifeeding phase. Artemia nauplii enriched with Algamac 3080 can enhance fish growth and reduce malformation. Fish fed Nanochloropsis enriched Artemia nauplii achieved higher survival, but higher jaw malformation. The present study demonstrates that nutritional enhancement in Artemia nauplii can significantly affect the performance of golden pompano larvae. Future study should focus on refining the optimum levels of dietary enrichment in golden pompano larvae to improve growth and survival, and decrease boney malformation of fish larvae.(5) The partial sequences of retinoid X receptors RXRα and RXRβ in golden pompano larvae were quantified. Nutrient enhancement can affect the jaw malformation of golden pompano larvae. RXRα is sensitive to nutrient enhancement,and can be used as an indicator to predict the possibility of jaw malformation in fish larvae.These work were focused on skeletal ontogeny, skeletal malformations and mechanism of mechanism for a systematic research, and such information would contribute to developing management strategies to improve production efficiency of this fish and related species in hatcheries.