Evaluation of the dietary Colour Enhancement Potential of the Yeast

Abstract- Ornamental fish keeping has become one of the most demanding and lucrative hobbies in the world. This increasing demand for ornamental fishes paved way for the growth of ornamental aquaculture sector with a trade value of more than 8 million US$ per annum. The colourations of fishes are the main factor contributing towards consumer preference. This study is an attempt to utilise Xanthophyllomyces dendrorhous yeast (a microbial source of carotenoids) effectively as a colour enhancer in ornamental fishes. The experiments were conducted in sword tail fish (Xiphophorus hellerii) which is a demanded live bearer.The experimental setup consists of 15 FRP tanks with 10 fishes in each tank. The inclusion level of the yeast were 2%(T1), 4%(T2), 6%(T3) and 8%(T4). A control group were also maintained (T0). Each feed were tried in triplicate. The results showed a significant change (P <0.05) in the colouration in each group when compared with the control group. It was confirmed using spectrophotometric and software based photo imaging analysis. From the spectrophotometric analysis the maximum carotenoid content of 8.81μg were observed from 8% yeast incorporated diets, followed by 6% yeast incorporated diets with 7.60μg carotenoids, 4% yeast incorporated diets with 6.08μg, 2% yeast incorporated diets with 5.44μg and the lowest for control with 4.37μg carotenoid content. Software based analysis analysed the RGB values of the fish photographs showing a maximum RGB value for 8% yeast incorporated diets, followed by 6%, 4%, 2% and lowest for the control. Completely Randomized Design was used as the statistical experiment. The best results were found in the group fed with 8% yeast incorporated diets. Along with the colouration studies growth studies were also done. There was a significant difference in the weight and length between treatment and days. The experiment proved the possibility of effective using of Xanthophyllomyces dendrorhous as a dietary carotenoid source in ornamental fishes.