Masahiko Takeda

Gustation and nutrition in fishes: application to aquaculture

Numerous studies on feeding stimulants for aquatic animals have been conducted in the last decade. Although fundamental knowledge has been accumulated (Jones, Chapter 14, this volume), there is little information on the relationship between gustation and nutrition in fishes and possible application of feeding stimulants to aquaculture. This chapter deals with the effects of feeding stimulants on fish nutrition and feeding, with special emphasis on their application to aquaculture. Previous studies on feeding stimulants have been reviewed by Atema (1980), Takeda (1980a, b), Bromley and Sykes (1985), Mackie and Mitchell (1985) and Smith (1989).

Origin of tunaxanthin in the integument of yellowtail (Seriola quinqueradiata)

Abstract 1. 1. Bioconversion of astaxanthin and lutein was examined by feeding experiments of yellowtail. 2. 2. Carotenoid contents in the integuments of the fish fed the diets supplemented with astaxanthin or lutein were markedly increased. 3. 3. In every test fish, the same nine carotenoids, tunaxanthins C, B and A, 3′-epilutein, lutein, zeaxanthin, diatoxanthin, cynthiaxanthin and β-carotene triol were detected. 4. 4. Astaxanthin was presumably metabolized to tunaxanthins C or B, via β-carotene triol, zeaxanthin and 3′-epilutein. Lutein seemed to be metabolized to tunaxanthins C or B, via 3′-epilutein. 5. 5. Sources of tunaxanthin in the integuments of marine fish were estimated to be astaxanthin, lutein and probably zeaxanthin all of which are very common carotenoids in marine organisms.