This feeding experiment was conducted to investigate the effects of dietary inclusion of various additives on growth performance, hematological parameters, fatty acid composition, gene expression and histopathological changes in juvenile olive flounder (Paralichthys olivaceus). Eleven isonitrogenous (49% crude protein) and isolipidic (10% crude lipid) experimental diets were formulated: no additives (Con); 5% kelp meal (Ke); 10% krill meal (Kr); 1% garlic powder (Ga); 1% citrus meal (Ci); 3% onion powder (On); 1% ginger powder (Gi); 1% mugwort powder (Mu); 1% licorice powder (Li); 1% wasabi powder (Wa); and a mixture (Mix) of these additives. Three replicate groups of juvenile flounder (average weight of 8.5 g) were fed one of the experimental diets to visual satiety twice a day for 15 weeks. The dietary inclusion of additives did not affect survival, weight gain, specific growth rate feed efficiency, daily feed intake, daily protein intake, protein efficiency ratio, hepatosomatic index and visceralsomatic index of the fish. Plasma triglyceride levels were significantly lower in fish fed the Ke, Ga, On, Gi, Mu, Li, and Mix diets than in fish fed the control diet. Plasma glucose, glutamic oxaloacetic transaminase and total cholesterol did not differ among dietary treatments. No significant difference was observed in fatty acid composition and lipid content of the dorsal muscle in fish fed the experimental diets. Myosin gene expression did not differ significantly among treatments after 5 weeks but was significantly lower in fish fed the Kr, Ci, Li, and Mix diets than in control group after 15 weeks. Histopathological analysis showed mild gill hyperplasia and mild necrosis of liver parenchymal cells in several individuals of each experimental group. These conditions were also observed in the control group and were not thought to be related to the inclusion of feed additives. The present findings indicate that the dietary inclusion of additives did not affect growth performance, fatty acid composition, gene expression, and histopathological changes in juvenile flounder. However, plasma triglyceride content may be reduced by supplementation with 5% kelp meal, 3% onion powder, 1% garlic powder, 1% ginger powder, 1% mugwort powder, and the additive mixture.

This study was conducted to select the media for the formalin killed vaccine (FKC) production of Vibrio harveyi and its application for olive flounder, Paralichthys olivaceus. For this, we have investigated the immune effects of Vibrio harveyi FKC vaccines grown in 3 different media i.e. Tryptic Soy Broth (TSB), TSB containing 2-2'-dipyridyl (TSB-D), Brain Heart Infusion Broth (BHIB) on the production of agglutinating antibody and protection against Vibrio harveyi in olive flounder. Additionally, a dual vaccine was prepared by combining Streptococcus parauberis vaccine to V. harveyi vaccine and its efficacy was also analyzed with the determination of optimal administration dosage. Consequently, olive flounder immunized with FKC grown in TSB-D showed the same protection with the vaccine grown in BHIB and the optimal dose of the vaccine was 10mg/kg of body weight. Indeed the dual vaccine showed higher agglutination titer and protection than control fish. The optimal dose for dual vaccine was 10mg/kg body weight for each of two vaccines.