Diet affects body color and energy metabolism in the Baikal endemic amphipod <em>Eulimnogammarus cyaneus</em> maintained in laboratory conditions

Proper diet is critical for laboratory-reared animals, as it may affect not only their welfare, but also experimental results. Amphipods (Crustacea: Amphipoda) play important roles in ecosystems and are often used environmental research. Endemic amphipods from the ancient Lake Baikal promising laboratory bioassays; however, there currently no cultures. In this work, we determine how different diets color metabolism of a amphipod, Eulimnogammarus cyaneus. We found that freshly collected blue-colored body correlated with total carotenoid content. Total levels did differ after long-term (two months) feeding close to natural carotenoid-enriched, or even carotenoid-depleted diet. Nevertheless, antennae was closer red natural-like group. It likely carotenoids commercial properly metabolized E. The animals fed had higher glycogen content, which signify metabolic rate. Overall, show carotenoid-enriched optimized decapods optimal amphipods, due compositions, rearing cyaneus other requires supplementation.