Citrus microcarpa extract as bio-immunostimulator for Edwardsiellosis in red hybrid tilapia culture

This paper described the application of Citrus microcarpa extract as bio-immunostimulator in red hybrid tilapia against Edwardsiellosis infection. Edwardsiellosis due to Edwardsiella tarda is one of the well-known bacterial diseases in aquaculture which leads to significant economic losses. The increasing antibiotic resistant cases among pathogenic bacteria led to many commercial antibiotics no longer effective in controlling bacterial diseases in aquaculture. Hence, in the present study was carried out to evaluate potential of C. microcarpa extract as immunostimulator against Edwardsiellosis infection in red hybrid tilapia. Comparison in terms of cumulative mortalities and antibody response against E. tarda among group of fish received C. microcarpa extract at different concentrations (CM1-1, 1 g kg-1 of fish; CM-2, 2 g kg-1 of fish and CM-4, 4 g kg-1 of fish) and group of fish received no medicated commercial feed (control) was carried out in the present study. Enzyme linked immunosorbent assay (ELISA) was used to monitor antibody response of fish that received medicated feed. The results of the present study showed that the values of antibody response against E. tarda of fish after seven days received C. microcarpa extract (CM-1, 0.113 ± 0.02 OD; CM-2, 0.14 ± 0.02 OD; CM-4, 0.173 ± 0.03 OD) were significantly higher (P < 0.05) compared to fish from group of control (0.0 OD). Whereas cumulative mortality of fish from group of control (53.3 ± 11.5 %) was significantly higher (P < 0.05) compared to fish from all of groups received C. microcarpa extract (CM-1, 13.3 ± 5.8 %; CM-2, 13.3 ± 5.8 % and CM-4, 6.7 ± 5.8 %). The results indicated the potential of C. microcarpa extract as immunostimulator in finfish culture.