The Pacific blue tang (PBT; Paracanthurus hepatus) is one of the most popular fish species sold to the marine ornamental aquarium trade. Although aquaculture has successfully produced this species, the only nutritional requirement known is the larvae require copepod nauplii in their diet. Long-chain polyunsaturated fatty acids (LC-PUFA), docosahexaenoic acid (DHA, 22:6n-3), eicosapentaenoic acid (20:5n-3; EPA), and n-6 LC-PUFA arachidonic acid (ARA, 20:4n-6) have effects on the egg and larval quality in aquaculture species. However, the effects of increasing LC-PUFA levels in PBT broodstock diets on egg and larval quality are unknown. A study was conducted to evaluate the effects of PBT broodstock nutrition on the quality of the eggs and larvae. Three experimental diets with different LC-PUFA concentrations: 3.5 % LC-PUFA (D3.5), 5% LC-PUFA (D5), and 6% LC-PUFA (D6) were fed to PBT broodstock for 7 months, the effects broodstock diets had on quantity and quality of PBT eggs and larvae was evaluated.
PBT egg production (P = 0.083) and fertilization percentage (P = 0.088) were not significantly different among diets. Egg hatching success (P = 0.022) and 3 dph larval survival (P = 0.031) were both significantly higher when broodstock were fed dietary LC-PUFA of 5% and 6%. Broodstock fed D5 and D6 produced significantly (P = 0.033) larger egg diameters, significantly (P = 0.028) larger oil globule diameters and significantly (P < 0.001) larger 3 dph larvae. 0 dph and 3 dph larvae from broodstock fed D6 had significantly (P= 0.001) larger oil droplet diameters. The different LC-PUFA concentrations affected the fatty acid composition of spawned eggs. High DHA and ARA concentrations in eggs improved egg and larval performance. A DHA:EPA ratio of nearly 2 in eggs was associated with improved larval quality. Results indicated that modifying the dietary PUFA content of PBT broodstock resulted in significant changes in egg and larval performance. Data suggested that increasing the LC-PUFA dietary content in PBT broodstock diets to 5% enhanced egg and larval quality.