Incorporation of dietary carotenoids into the fins of yellow- and red-finned Eurasian perch Perca fluviatilis

Abstract

The colour of the ventral, anal and caudal fins of Eurasian perch can range from pale yellow to intensered. Within spatially separated populations, however, individuals are usually very uniform in colour.We fed astaxanthin- and canthaxanthin-enriched dry feed to juvenile perch from a yellow-finned and ared-finned population to compare the influence of dietary carotenoids on fin colour between these twopopulations. In this way we wanted to test whether fin colour in perch is predominantly a phenotypicallyplastic trait or whether differently coloured individuals represent colour morphs. The ventral fins of perchfrom the red-finned population always exhibited significantly more intense redness when their feed wassupplemented with either one or both carotenoid additives. Perch from both populations deposited morecanthaxanthin in their ventral fins than astaxanthin, red-finned perch in particular. Yellow-finned perchprobably converted canthaxanthin into -carotene, which was the dominant carotenoid in their ventralfins, whereas the fins of red-finned perch contained only trace amounts of -carotene. We conclude thatthese two populations represent colour morphs that differ fundamentally in their ability to metaboliseand deposit dietary carotenoids into their ventral fins. Considering the multiple physiological functionsof carotenoids, these fundamental differences in carotenoid metabolism between perch colour morphsmay have far-reaching consequences for the performance of different populations, for example in theirresponse to parasite infections.