FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

Tilapia is now the primary product of the aquaculture industry in Taiwan. Red tilapia (Oreochromis sp.) was mutated from the Mozambique tilapia species. The purpose of this study was to explore the effects of dietary carotenoid supplements on the integument pigmentation of red tilapia (Oreochromis sp.). Experiments were conducted to provide two different sources of carotenoids: gene transferred Escherichia coli powder and synthetic astaxanthin. The mean weight of the red tilapia tested was about 2.6 g. Fish were divided into five groups with differing experimental diets: a control group (Ctrl), an E-50 group, an E-100 group, an R-50 group, and an R-100 group. The diets of the fish in the E-50 group and the E-100 group were supplemented with gene transferred Escherichia coli powder with two different carotenoid contents, 50 and 100 mg/kg, respectively. The diets of the fish in the R-50 group and the R-100 group were supplemented with synthetic astaxanthin at 50 and 100 mg/kg, respectively. The duration of the experiment was 10 weeks. Fish integument was measured with a tristimulus colorimeter, and further quantified for skin pigment. The results suggested that carotenoid supplements did not have obvious effects on the growth performance and feed efficiency, but did improve pigmentation by enhancing a and b values in the red tilapia. In this trial, the △E varied from 8.06 to 14.89, while the content of carotenoids in the red tilapia tested varied from 0.25 to 0.84 mg/100 g.