Effects of Increasing Docosahexaenoic Acid (DHA) and Arachidonic Acid (ARA) in Brood Diets of Monodactylus sebae on Fecundity, Egg and Larval Quality, and Egg Fatty Acid Composition

The Guinean Fingerfish Monodactylus sebae is a popular euryhaline ornamental fish species with limited aquaculture production. One of the bottlenecks to commercial production is lack of knowledge of the nutritional requirements for broodstock. Therefore, three broodfish diets were formulated and fed to Guinean Fingerfish broodstock to determine their quantitative and qualitative effects on egg production and egg and larval morphology. The dietary treatments consisted of a control, a diet with increased docosahexaenoic acid (DHA), and a diet with increased DHA and arachidonic acid (DHA + ARA). Broodfish fed the DHA + ARA diet spawned more frequently than broodfish fed the DHA diet and those fed the control diet. The greatest egg production was also observed from broodfish fed the DHA + ARA diet. The mean hatching success of floating eggs was not significantly different among diets. The mean egg and oil globule diameters for both floating and sinking eggs were significantly smaller for broodfish fed the DHA + ARA diet rather than the other diets. At both 24 and 48h, survival was significantly greater for fish fed the control diet than for those fed the DHA and DHA + ARA diets. At both 24 and 48h posthatch, notochord length was significantly shorter for larvae from broodfish fed the DHA + ARA diet than for larvae from fish fed the control diet. The fatty acid profiles of the eggs closely resembled the fatty acid profiles of the diets with respect to DHA and ARA levels. Guinean Fingerfish females appear to have the ability to regulate the levels of DHA and ARA assimilated into developing eggs, although there is not clear evidence that they can elongate and desaturate C18 fatty acids into DHA and ARA. Received April 23, 2012; accepted October 27, 2012