Carotenoid pigments are found in the gut wall, fat cells and ovary of Daphnia. A carotenoid-protein is sometimes present in the blood; the amount varies during an instar. The carotenoid-protein in the eggs of Daphnia and certain other Cladocera undergoes a change when the embryos are fully developed. The protein link is broken and the freed carotenoid leaves the cytoplasm of the fat cells and intensifies the colour of the fat globules. Light promotes the deposition of carotenoids in the fat cells and eggs of Daphnia magna. Females reared in the light contain three times as much carotenoid as similarly fed females reared in the dark. The carotenoid pigments of D. magna have been identified as $\beta $-carotene, $\gamma $-carotene, lutein (esterified), and astaxanthin (part esterified). This is the first record of $\gamma $-carotene in a crustacean.