Fermented meal from dead fish and citrus peel, a promising fish feed

According to research from the Cheju National University, on a paper presented at Aquaculture America 2008, tons of citrus peel by-products from the citrus juice processing in Korea, plus dead fish from commercial-scale aquaculture farms, can be turned into a highly valuable aquafeed, easing at the same time the enormous economical loss for both industries, and considerable environment damage. Dr Seon-Heui Cha and his team from the Faculty of Applied Marine Science at the Cheju National University performed trials, which included fermented fish meal (FFM) made by dead fish and citrus peel. They prepared two FFM's, one containing citrus peel and the other containing rice bran (without citrus peel). The citrus peel containing FFM extract showed strong scavenging activities against DPPH free-radical (about 95%) and hydrogen peroxide (around 80 %) in a concentration of 4 mg/ml. Also, the FFM containing citrus peel exhibited remarkable protecting effects to flounder leukocyte against H2O2-mediated DNA damage. DR Cha formulated two experimental diets for olive flounder; one a raw fish moisture pellet (MP) diet and the other MP diet mixture with 7% FFM containing citrus peel in a commercial-scale aquaculture. The fish feeds including FFM enhanced the growth and significantly decreased the mortality (p<0.05) of olive flounder fish. Fish fed with FFM had higher lysozyme activity (p>0.05) and NBT reduction (p<0.05). The results suggested that citrus peel containing FFM increased the immune response in cultured olive flounder.