Rabbitfish Integration in Offshore Gilthead Seabream Polyculture: Improving Growth Performance, Reducing Disease Burden, and Mitigating Biofouling in Tropical Aquaculture

Abstract Gilthead seabream ( Sparus aurata ) is one of the most commercially significant species in the Mediterranean and Middle Eastern marine aquaculture, yet intensified production systems expose this species to persistent challenges, including net biofouling, parasitic disease, and reduced growth efficiency. This case study is based on research conducted over two full production cycles (2023–2024) in open-sea cages at Omega Fish Farm, Dadna, Fujairah, United Arab Emirates. The study compared six cages of seabream monoculture with six cages of polyculture incorporating white-spotted rabbitfish ( Siganus canaliculatus ), a herbivorous species with well-documented grazing activity on algal and invertebrate fouling organisms. Key production indicators, including growth rate (GR), specific growth rate (SGR), feed conversion ratio (FCR), feeding rate, and mortality, were assessed throughout the production cycles using area under the curve (AUC) analysis. Biofouling biomass, annelid abundance, and seabream net-biting frequency were evaluated during the first six months of each production cycle. Overall, polyculture significantly improved seabream production performance compared with monoculture and significantly reduced net biofouling biomass, annelid abundance, and seabream net-biting frequency. Enteromyxum leei infection prevalence and severity were also reduced in polyculture cages. During the highest-risk period, peak prevalence was 29.4%, with a median infection degree of 2.5, compared with 49.8% and 4.0, respectively, in monoculture cages. In addition, net replacement intervals were extended to 344 days under polyculture compared with 196 days under monoculture. These findings demonstrate that integrating rabbitfish into offshore seabream production can simultaneously improve production performance, reduce biofouling and parasitic disease burden, and extend net service life, providing a biologically sound and operationally practical strategy for enhancing the sustainability of marine aquaculture in tropical environments. Information © The Authors 2026