Submitted to: North American Journal of Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/27/2013
Publication Date: 5/10/2013
Citation: Ohs, C.L., Dimaggio, M.A., Grabe, S.W., Broach, J.S., Watson, C.A., Breen, N.E., Barrows, F. 2013. Effects of increasing docosahexaenoic acid and arachidonic acid in brood diets of monodactylus sebae on fecundity, egg and larval quality, and egg fatty acid composition. North American Journal of Aquaculture. 75:285-294, 2013. Interpretive Summary: Development of nutritionally complete diets for fish during the reproductive stage of life is particularly difficult due to the large size of fish, in the case of trout and salmon, and the long periods of time required. One of the most expensive and increasingly unavailable nutrients in the diet is essential fatty acids. These nutrients have been provided by the addition of fish oil in the past, but those supplies are very limited and not expected to increase again. The purpose of this research was to determine which of the essential fatty acids found in fish oil is the most important for reproduction. Feeding a diet with just one of the fatty acids resulted in more frequent spawning and the greatest egg production. However, young fish from these parents were smaller than the control fish. Results of this study demonstrate that fatty acids are an important factor in broodstock diets and there are alternatives (although not presently cost effective) to fish oil.
Technical Abstract: Monodactylus sebae is a popular euryhaline ornamental fish species with limited aquaculture production. One of the bottlenecks to their commercial production has been knowledge of broodstock nutritional requirements. Therefore, three brood diets were formulated and fed to M. sebae brood to determine the effects of feeding these diets both quantitatively and qualitatively on egg production and egg and larval morphology. The dietary treatments consisted of a control, a second diet with increased docosahexaenoic acid (DHA), and a third diet with increased DHA and arachidonic acid (DHA+ARA). Results indicate that 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 compared to the other diets. 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 compared to the other diets. At both 24 and 48 h, survival was significantly greater for the control diet than the DHA and DHA+ARA diets. At both 24 and 48 hours post hatch, notochord length was significantly shorter for larvae from broodfish fed the DHA+ARA diet compared to 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. M. sebae 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.