A method of enhancing a culturing characteristic of fish larvae, including administering to said larvae in a nutritional diet essential fatty acids including DHA and AA in a ratio effective to enhance the culturing characteristic of such fish larvae relative to a corresponding nutritional diet lacking DHA and AA. The culturing characteristic may be at least one of stress resistance, immunoresistance, hatching rate, and growth rate. In a preferred aspect, the DHA and AA together comprise from about 10 to about 30% of total fatty acids in enrichment lipids, and the dietary ratio of DHA: AA is less than 10. The invention also contemplates a method of operating an aquaculture facility, including growing heterotrophic algae and/or fungi in a fermentor under growth conditions therefor, to produce a heterotrophic cellular product containing DHA and AA, and feeding the heterotrophic cellular product and/or one or more components thereof to (i) fish larvae and/or broodstock in the aquaculture facility, or (ii) live food subsequently fed to such fish larvae.