Despite the well known importance of ω-3 polyunsaturated fatty acids (PUFA) in marine and freshwater fish larvae, there are few studies on how essential fatty acid requirements and composition on whole body can be altered by changes in water salinity. The present study aimed to determine the effect of salinity on ω-3 PUFA requirements, larval growth survival and fatty acid composition of G. maculatus larvae cultured at two different salinities (0 and 15 g∙L-1) for 20 days while fed rotifers containing two different levels of ω-3 PUFA (1.87 and 3.16%). The results denoted a marked difference in ω-3 PUFA requirements and in the pattern of fatty acid deposition in the whole body of larvae reared at different salinities, depending of ω-3 PUFA in diets. Thus, to improve growth and survival larvae of G. maculatus reared at 0 g∙L-1 require higher levels of ω-3 PUFA, principally 18: 3ω-3. Larvae reared at salinities of 15 g∙L-1 require low levels of ω-3 PUFA for optimal survival, especially 18: 3ω-3.  Eicosapentaenoic acid and docosahexaenoic acid content in the whole body of larvae was also affected by water salinity.ABSTRACT. Despite the well known importance of ω-3 polyunsaturated fatty acids (PUFA) ​​in marine and freshwater fish larvae, there are few studies on how essential fatty acid requirements and composition on whole body can be altered by changes in water salinity. The present study aimed to determine the effect of salinity on ω-3 PUFA requirements, larval growth survival and fatty acid composition of G. maculatus larvae cultured at two different salinities (0 and 15 g∙L-1) for 20 days while fed rotifers containing two different levels of ω-3 PUFA (1.87 and 3.16%). The results denoted a marked difference in ω-3 PUFA requirements and in the pattern of fatty acid deposition in the whole body of larvae reared at different salinities, depending of ω-3 PUFA in diets. Thus, to improve growth and survival larvae of G. maculatus reared at 0 g∙L-1  require higher levels of ω-3 PUFA, principally 18: 3ω-3. Larvae reared at salinities of 15 g∙L-1 require low levels of ω-3 PUFA for optimal survival, especially 18: 3ω-3.  Eicosapentaenoic acid and docosahexaenoic acid content in the whole body of larvae was also affected by water salinity.