Abstract
In glass eels (54 mm TL; 0.018 g) of the Australian shortfin eel Anguilla australis the fatty acid composition was typical of marine species, with a n‐3 to n‐6 ratio of 5.3, a low level of mono saturated fatty acids (monoenes) and a high level of polyunsaturated fatty acids (PUFA). In elvers (pigmented: 56 mm TL; 0.028 g), the n‐3 to n‐6 ratio was 2.6. In elvers monoenes, as per cent of all identifiable fatty acids, increased to 30.9% from that of 19.8% in glass eels. The fatty acid composition of juvenile eels, reared from the original stock of glass eels and elvers, in outdoor, fertilized ponds, with (115 mmTL; 2.2 g) and without feeding (110 mmTL; 1.9 g), had a fatty acid composition typical of freshwater species, with a n‐3 to n‐6 ratio 1.9 and 1.3, and 37.7 and 46.5% of monoenes in unfed and fed groups respectively. A principal component analysis summarized efficiently the progressive changes in fatty acid composition from the glass eel to juvenile eel stage. The observed changes in the fatty acid of the different developmental stages in Australian shortfin eel are discussed in relation to physiological changes associated with the diadromous habit.