Artemia eggs and nauplii from different locations were analysed for fatty acids in order to clarify their food value to fish. The results demonstrated that
Artemia could be classified into two types by the fatty acid composition; one contained a high amount of 18:3ω3, which is the essential fatty acid (EFA) for freshwater fish, and the other was high in the content of 20:5ω3, which is one of the EFA (together with 22:6ω3) for marine fish.
Artemia from San Francisco in 1975 and 1976 and from South America in 1977 were found to be high in the content of 18:3ω3 and quite low in the content of the EFA for marine fish, suggesting a poor food value to marine fish. On the other hand, the concentration of 20:5ω3 was high in
Artemia from San Francisco and Canada in 1977, and they were found to be satisfactory as a living feed for red sea bream juveniles. The dietary value of
Artemia nauplii was improved by feeding them marine
Chlorella and yeast supplemented with cuttlefish liver oil, both containing high amounts of the EFA of marine fish. The starvation of newly hatched
Artemia nauplii containing a high amount of 18:3ω3 showed that the lipid and 18:3ω3 contents significantly decreased and the level of 20:5ω3 increased. This may suggest the conversion of 18:3ω3 in
Artemia nauplii, to 20:5ω3, to some extent, but not to 22:6ω3. Thus the present study has demonstrated that the class of EFA contained in
Artemia is the principal factor in the food value of
Artemia to fish.
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