Two feeding trials were conducted to determine the effects of dietary supplementation with Hizikia fusiformis or Ecklonia cava on the non-specific immune responses of parrot fish Oplegnathus fasciatus. Fish were fed experimental diets to which H. fusiformis or E. cava powder were added to final concentrations of 0, 2, 4 and 6%, respectively. After feeding for two weeks, phagocytic activity was significantly higher in fish fed diets containing H. fusiformis, but not E. cava, than in fish fed the basal diet. Lysozyme activity was significantly increased in the fish fed diets containing 6% H. fusiformis and E. cava. Myeloperoxidase activity was also significantly higher in fish fed diets containing 2 and 4% H. fusiformis, as compared to the basal diet, but not in those fish fed E. cava. These two studies indicate that dietary supplementation with H. fusiformis or E. cava could enhance the innate immune responses of parrot fish during their growth stage.