In Taiwan, the mushroom Antrodia camphorata (AC) is used for medicinal purposes, including cancer prevention and treatment. This study aimed to investigate the effect of AC-supplemented diets on the innate immunity and disease resistance of the orange-spotted grouper Epinephelus coioides against two bacterial infections—Vibrio alginolyticus and Streptococcus iniae. Orange-spotted groupers were fed AC-supplemented diets at 0 (control), 1.5, 3.0, 4.5, and 6.0 g kg⁻¹ for 28 days and examined for innate immune responses and survival rates against V. alginolyticus and S. iniae. The results showed that the innate cellular and humoral immune parameters, including respiratory burst, phagocytic activity, and lysozyme activity of leukocytes, along with serum alternative complement activity (ACH₅₀) and superoxide dismutase activity, as well as interleukin (IL)-4 and IL-6, were all significantly increased in groupers fed AC-supplemented diets. Groupers fed diets containing AC at doses higher than 3.0 g kg⁻¹ had better survival rates than the control group 3–18 days after V. alginolyticus or S. iniae challenge. The enhanced disease resistance may be attributable to AC-induced innate immunity, suggesting that utilizing AC as a dietary supplement at 3.0 g kg⁻¹ may enhance the disease resistance of orange-spotted groupers against Vibrio or Streptococcus infection.

Mercury (Hg) is a dangerous heavy metal that can accumulate in fish and is harmful when consumed by humans. This study investigated the bioaccumulation of mercury in the form of methylmercury (MeHg) and evaluated nonspecific immune responses such as phagocytic activity and superoxide anion (O₂⁻) production in hybrid grouper (Epinephelus fuscoguttatus × E. lanceolatus). The hybrid grouper leukocytes were incubated with methylmercury chloride (CH₃HgCl) at concentrations of 10–10,000 µg/L to determine cell viability, phagocytic activity, and O₂⁻ production in vitro. Subsequently, the grouper were exposed daily to CH₃HgCl mixed in the experimental diets at concentrations of 0, 1, 5, and 10 mg/kg for 28 days. The bioaccumulation of MeHg in the liver, head kidney, and muscle tissue was measured, and the phagocytic activity and O₂⁻ production were evaluated. In vitro results indicated that cell viability was significantly lower than that of the control group at concentrations > 500 µg/L. The phagocytic rate and O₂⁻ production at concentrations ˃ 500 and ˃ 200 µg/L, respectively, were significantly lower than those of the control group. The dietary exposure demonstrated that MeHg accumulated more substantially in the liver and head kidney compared with the muscle tissue in the treatment groups. Moreover, the cumulative concentration significantly increased with higher concentrations and more days of exposure. The phagocytic rate and O₂⁻ production in the treatment groups were significantly lower than those in the control group from days 2 and 1, respectively. In conclusion, hybrid grouper accumulated significant MeHg in the liver and head kidney compared with the muscle tissue, and higher concentrations and more exposure days resulted in decreased cell viability, phagocytic activity, and O₂⁻ production.