| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 100 === This study used blood parrot (Cichlasoma synspila × C. citrinellum) as the experiment model fish to test on color enhancement of different diets. Two experiments were done with 12 fishes in one tank and 4 fish was marked by cutting the fish’s fin. In experiment one, blood parrot was fed with four different commercial diets (BA, BB, BC and BD) and six diets contain 0, 100, 300, 400 and 500mg/kg of synthetic astaxanthin labeled as A0, A100, A300, A400 and A500. The fish were weight and photographed weekly. After seven weeks, commercial diets contain astaxanthin (BC and BD) showed increase of red color on fish body significantly; while the other two feeds (BA and BB) which contain no astaxanthin did not show any color enhancement. After 49 days of feeding experiment, a* value were BC≥(BD=A100=A200=A400=BB=A500)>BA=A0, which stated that diet with 100mg/kg of astaxanthin was effective to enhance red coloration of blood parrot fish but still commercial diet BC showed the best result of red color enhancement. After 21 days of fading experiment, L* value and b* were increase but a* value was decline for all treatment. For experiment two, blood parrot was fed with diet contained 0, 30, 60, 90, 120 and 150mg/kg of astaxanthin (A0, A30, A60, A90, A120 and A150) and diets contain 4mg/kg of methyl testosterone mix with 60, 90, 120 and 150mg/kg of astaxanthin (TA60, TA90, TA120 and TA150) and commercial diet BC. The tested fish were treated as experiment 1. The fish was weighed every 10 days and photographed every five days. After seven weeks of feeding experiment, a* value was BC>TA150> TA120≧TA60=A150=A60=TA90=A90=A120≧A30>A0. Results analyzed showed that astaxanthin and methyl testosterone enhanced coloration of fish significantly. Diet contains 4mg/kg of methyl testosterone mixed with 150mg/kg of astaxanthin showed the best result of red color enhancement but still not comparable to the commercial diet BC. Fading experiment (40 days) also had the similar result with experiment one. Saturation of a* value was reached around three weeks in both experiment. The rising curvature of A0 was significant lower than the other diets but there were no significant different within others treatment. Diets contain astaxanthin were not affected the growth of blood parrot, but methyl testosterone may lead growth retardation of blood parrot.
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