Abstract
Stable isotope ratio of essential fatty acids (EFA) is expected to be a useful tool for analyzing food web, however the isotopic fractionation between animals and food source in each EFA has not been revealed yet. In order to obtain those coefficients, a 100-day feeding experiment was conducted on zebrafish (Danio rerio) by using a commercial food source. From the results, it was revealed that each isotope ratio of 18:2n-6, 20:5n-3 and 22:6n-3 of zebrafish was approaching asymptotically to those of food source during experiment at 100-day and there were no significant difference between zebrafish and food source. However, stable isotope ratio of 20:4n-6 in zebrafish showed wide range of fractionation among each individual. This result was considered that metabolism of 20:4n-6 from 18:2n-6. These results indicate isotope ratio of EFA is useful tool to infer assimilated food sources.
