Immune protection by Rhizophora apiculata in clownfish against Vibrio alginolyticus

The effect of dietary supplementation with Rhizophora apiculata leaf extract on innate immune response, survival rate, and mortality of the economically important ornamental clownfish, Amphiprion sebae against Vibrio alginolyticus is reported. When fed with 1%, 5%, and 10% enriched diets the specific growth rate (SGR) of challenged A. sebae decreased progressively while the feed conversion ratio (FCR) increased from weeks 1 to 4. The lysozyme, respiratory burst, complement and phagocytic activities significantly increased when infected fish were fed with 5% or 10% supplementation diet on weeks 3 and 4. The superoxide anion production increased significantly with 1%, 5% and 10% diets on weeks 3 and 4 while the serum bactericidal activity significantly increased with all enriched diets. The anti-protease activity registered a significant increase with 5% and 10% diets on week 3 while with all enriched diets on week 4. The maximum survival rate was 85% and 80% when the challenged fish were fed with 5% and 10% enriched diets, but it declined to 65% with 1% diet. A lower cumulative mortality of 15% and 20% was registered when infected fish were fed with 5% or 10% diets. The results suggest that feeding 5% or 10% R. apiculata extract supplementation diet positively enhance the immune response and improve the growth and survival rate of A. sebae against V. alginolyticus.