Effects of Putative Growth or Health-Enhancing Dietary Additives on Juvenile Olive Flounder, Paralichthys olivaceus, Performance

The effect on growth and body composition of various dietary additives with putative growth or health-enhancing properties were determined in juvenile olive flounder (25 g initial weight). Nine experimental diets were prepared to contain one of the following additives: control (Con) with no additive, Opuntia ficus-indica ver. saboten (OF), propolis (PP), lactic acid bacteria (LA), gamma-poly-glutamic acid (PG), onion extract (OE), organic sulfur (OS), Biostone (R) (BS), and fig extract (FE). Fishmeal, dehulled soybean meal, and corn gluten were used as the protein source of the experimental diets. Wheat flour and soybean oil were used as the carbohydrate and lipid sources, respectively. Dietary additives were included in each experimental diet at 1% at the expense of wheat flour except for the FE (aqueous), which was substituted at 1% of the amount of water added to the diet. Fish were hand-fed to satiation twice a day for 6 d/wk for 6 wk. Weight gain of fish fed the OE diet was higher than that of fish fed with the PP diet. Chemical composition of fish was not different among the experimental diets. OE was the most effective dietary additive to improve performance of olive flounder among additives used in this study.