To develop more efficient culture techniques of Pacific bluefin tuna (PBF, Thunnus orientalis), it is important to manage fish welfare. Blood examination could be a useful tool to check fish health condition. This study investigated the effect of common rearing factors such as anesthesia, excess exercise and feeding on blood properties and chemistries of cultured PBF juvenile. Results of this study showed that anesthesia treatment significantly induced blood acidosis and red blood cell (RBC)

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... lling, thus anesthesia should not be used for PBF juveniles to examine their health condition. Even though excess exercise and feeding did not influence blood pH, partial pressure of O 2 or CO 2 , RBC count was significantly decreased and mean corpuscular volume increased after excess exercise and feeding. In addition, electrolyte concentrations such as Na + , Cland Ca 2+ in the blood increased after excess exercise and feeding. Hence, this study suggests that blood collection from PBF juveniles should be conducted before feeding and that anesthesia should be avoided to minimize negative physiological effects.