Effects of dietary different carotenoids supplements on pigmentation of two kinds of Lake Malawi Cichlids (Labidochromis caeruleus and Metriaclima estherae var. Red）

This study focused on the different kinds and concentrations of carotenoid in diet, for effects of pigmentaion of two kinds of Lake Malawi cichlids, Labidochromis caeruleus and Metriaclima estherae, assessment of pigment metabolism, and raise fish pigmentaion in the suitable amount. Experimental feeds are supplemented with two kinds of different carotenoid: zeaxanthin (hereinafter referred to as Z), astaxanthin (hereinafter referred to as A). The experiment period was total 40 days. In the pigmentaion experiments , two kind of fish were divided into nine groups respectively: control, A12.5, A25, A37.5, A50, Z12.5, Z25, Z37.5, and Z50 (mg/kg diet). Fish skin were tested with tristimulus colorimeter, and further quantified for integument pigment. The experimental results indicate that the carotenoids have no effects on growth and feed efficiency, but improve pigmentation in L. caeruleus and M. estherae. In the pigmentaion experiments, the color difference values (∆E) varied from diets contained carotenoids to control, and are below 6.0 generally. The content of carotenoids in integument of L. caeruleus vary from 4.36-8.86mg/100 g and have the lowest average on the control group . The amount of carotenoids in the skin increased with the increasing carotenoid concentration of feeds; The amount of carotenoids in the skin of M. estherae had no significant difference in average 5.51 ~ 8.86mg / 100g between experimental groups and control group. The ability is more effective in astaxanthin than zeaxanthin to affect the pigmentation in this two species. It is recommended that the optimal concentration of astaxanthin is 25~37.5mg/kg diet and zeaxanthin is 12.5~25mg/kg diet for L. caeruleus ; the optimal concentration of astaxanthin is 12.5mg/kg diet and zeaxanthin is 12.5~50mg/kg diet for M. estherae.