POTENTIAL USE OF CINNAMON Cinnamomum sp. AS PHYTOBIOTICS FOR ORNAMENTAL FISH  

Phytobiotics are plant-derived substances that enhance the innate immune system of the animal. Immunostimulants are used as prophylactic measures and are possible alternatives to the use of chemotherapeutants such as antibiotics. Recently, phytobiotics are gaining popularity in aquaculture as a means of stimulating the immune responses of both fish and crustaceans. Previous studies demonstrated the beneficial effects of a commonly used spice, cinnamon, Cinnamomum sp. Cinnamon is known for its antimicrobial effects, and when incorporated in the diets of some food fish, this spice enhanced the growth performance and feed utilization. However the effects of cinnamon as an immunostimulant has not been widely studied in ornamental fish. Hence, these series of studies determined the effectiveness of cinnamon as an immunostimulant in ornamental fishes both in vitro and in vivo.

Commercially available cinnamon powder was obtained and a medicated ornamental fish feed using 1% of the fine powder was prepared by top dressing. Dietary administration of the medicated feed to two popular ornamental fish species, namely guppy, Poecilia reticulata and platy, Xiphophorus maculatus was done at 8% body weight for 15 days. Fish fed with the non-medicated feed were used as control for the experiment. Selected immune responses and anti-oxidant activity from tissue homogenates of the fish were assessed at 0, 3, 7 and 15 days during feeding. Experimental bath challenge with a bacterial pathogen was done after the duration of feeding with the medicated feeds and efficiency of the phytobiotics in protecting the fish was assessed by the relative percentage survival. Bacterial clearance and detection of the pathogen from the infected survivors was done by streaking tissues samples onto thiosulfate-citrate-bile salts (TCBS) agar.

Preliminary results showed modulation of the innate immune responses and anti-oxidant activities following dietary administration of cinnamon and the responses were species-dependent. Significant protection in the treated fish was observed following infection with a pathogenic bacterium in comparison with the control fish. Lower incidence of the bacterial pathogen was also obtained in infected survivors fed with the medicated feed compared with the infected control fish. Taken together, these results demonstrated the beneficial effects of cinnamon in ornamental fish by boosting their immune responses could further be developed as an immunostimulant for the ornamental fish industry.