Carotenoids in food chain between freshwater fish and aquatic insects

The freshwater fish, Japanese char, dolly varden, masu trout, common freshw ater goby, Chinese minnow, etc., feed on mainly aquatic insects and it is a ssumed that beta, beta-caroten-2-ol isolated from the fish described above presumably arises from their aquatic insect food. We investigated the relat ionship of carotenoids between freshwater fish and their representative aqu atic insect food. The twenty known carotenoids were obtained from aquatic i nsect. beta, beta-Carotene, lutein A: (3R, 3'R)-zeaxanthin, fucoxanthin and fucoxanthinol were the principal carotenoids. From the five of seven speci es of aquatic insects examined, a small amount of beta, beta-caroten-2-ol w as isolated, and it was considered to be an oxidative metabolic products of beta, beta-carotene which is taken in with their food algae. Furthermore, we carried out feeding experiments on freshwater fish, Chinese minnow with fucoxanthin, the principal carotenoid of aquatic insects, as a test group. There was no accumulation of fucoxanthin in Chinese minnow. This fact might be applicable not only to Chinese minnow but also all species of freshwate r fish. (C) 1999 Elsevier Science Inc. All rights reserved.