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A 12-wk feeding trial was conducted to evaluate the essentiality of choline supplementation in diets for parrot fish. Five isonitrogenous and isocaloric diets were supplemented with 0 (as control), 500, 1,000, and 2,000 mg choline per kg diet, and a positive control diet without choline contained 0.3% of 2-amino-2-methyl-1-propanol as choline biosynthesis inhibitor (designated as Con, C500, C1000, C2000 and Con+, respectively). Triplicate groups of fish (body weight, 8.8±0.01 g) were fed one of the experimental diets at a rate of 4% body weight twice daily. The fish fed Con+ diet revealed significantly lower growth performance and feed utilization efficiency than other fish groups. Supplementation of choline to the basal diet did not significantly influence fish growth. The highest liver lipid content was observed in fish fed the Con+ diet and inversely correlated with liver choline concentration although the differences were not significant. Also, significantly higher liver linoleic, eicosapentaenoic and docosahexaenoic acid contents were found in fish fed the Con+ diet. Innate immune parameters including respiratory burst and myeloperoxidase activities were not significantly affected by dietary choline levels. The findings in this study conclude that choline concentration of approximately 230 mg kg−1 diet meets the requirement of parrot fish.

A 15-wk feeding trial was conducted to examine the supplemental effects of Barodon on growth performance, gastrointestinal histology, feed digestibility and innate immunity in olive founder. A basal commercial diet was used as a control and two other diets were prepared by spraying 0.1% or 0.2% of Barodon. Triplicate groups of fish (BW, 145 g) were fed one of the test diets to apparent satiation twice daily. At the end of the feeding trial, fish growth performance was not significantly affected by dietary treatments; however, feed utilization was significantly improved (linear and quadratic, p