“Efficacy of a phytobiotic-based additive in controlling natural ectoparasite infestations in farmed grouper, Epinephelus fuscoguttatus (7007)”

Efficacy of a phytobiotic-based additive in controlling natural ectoparasite infestations in farmed grouper, Epinephelus fuscoguttatus

Ectoparasitic infections are a major health challenge in grouper (Epinephelus fuscoguttatus) farming in Asia, particularly during the early stages of culture. Parasites such as Zeylanicobdella, Caligus, Trichodina, and Dactylogyrus infest the gills, skin, and mucus, causing lesions that facilitate secondary bacterial invasion by opportunistic pathogens like Vibrio spp. This co-infection impairs fish health, compromises immunity, and reduces growth and survival.

This study evaluated the efficacy of APEX (Adisseo), a phytobiotic-based additive designed to support skin immunity and resilience under farming conditions. Juvenile groupers (8 ± 0.5 g) were stocked at 75 fish per hapa, in triplicate, and reared in open-water conditions for 90 days. Fish were fed diets supplemented with 0, 3, or 7 g/kg of APEX via top-coated pellets.

The functional additive significantly reduced parasite prevalence (percentage of infected fish) and mean intensity (average number of parasites per infected fish). In both the medium- and high-dose treatments, Zeylanicobdella and Dactylogyrus prevalence remained below 10%, while Caligus and Trichodina prevalence dropped to 11% and 9%, respectively, compared to 71-87% in the control group. Mean intensity was also significantly reduced, indicating not only fewer infected fish but also milder infections. As the ectoparasite burden decreased, Vibrio spp. loads in both kidney and skin tissues dropped by over 80%. These pathogen reductions corresponded with enhanced immune responses. Hematological parameters, including red and white blood cell counts, hemoglobin, lymphocytes, and monocytes, increased by 10-20% in the medium-dose group and 25-40% in the high-dose group, reflecting improved systemic immunocompetence under farm stress conditions.

Consequently, fish showed improved performance, with daily weight gain increasing by up to 14%, FCR improving by 10%, and morphometric indices (length, thickness, and condition factor) significantly enhanced. These findings demonstrate that APEX improves health status and productivity in grouper farming through integrated pathogen control and immune support.

1. CHEN, I-TUNG, Adisseo France SAS, Presenter
2. ISERN-SUBICH, MARIA MERCÈ, Adisseo France SAS, Author
3. NUEZ-ORTÍN, WALDO G., Adisseo France SAS, Author