The effect of fucoidan or potassium permanganate on growth performance, intestinal pathology, and antioxidant status in Nile tilapia ( Oreochromis niloticus )

Fucoidans are marine algal sulfated glycans that are widely used as dietary additives in aquaculture. These glycans are recognized as beneficial supplements for their antimicrobial, anti-inflammatory, anticancer, and antiviral properties. Potassium permanganate is another commonly used chemical that is used in aquaculture to treat infections in fish. Despite their widespread use, there are few data available regarding the potential sublethal toxicity associated with fucoidan and potassium permanganate treatments of fish. In this study, we investigated the effect of each compound on the growth, intestinal health, and antioxidant status of Nile tilapia ( Oreochromis niloticus ). Both compounds affected the growth of experimental fish compared with untreated fish. However, while growth parameters were positively associated with the dose of fucoidan administered, growth was negatively associated with the dose of potassium permanganate in Nile tilapia. Fucoidan treatment was observed to improve the intestinal health of fish based upon increases in intestinal villous area, intestinal villous length and width, and the intraepithelial lymphocyte number and decreases in the total intestinal bacterial count compared with untreated fish. Conversely, potassium permanganate induced intestinal epithelium proliferation and villous branching, a histopathological response typically observed with chemical irritants. Both fucoidan and potassium permanganate decreased levels of oxidative and nitrosative stress markers and enhanced the antioxidant status in multiple organs. Taken together, fucoidan dietary application improved the growth, intestinal health, and antioxidant status in Nile tilapia, supporting the use of this compound as a promising feed additive for aquaculture production. Conversely, potassium permanganate baths have negative effects on fish growth at higher doses and appeared to act as a gastrointestinal irritant in tilapia. This study improves knowledge regarding the biochemical and histological responses in Nile tilapia to two widely used aquaculture-related treatments.