Chitosan for Aquaculture: Growth Promotion, Immune Modulation, Antimicrobial Activity, Bio-Carrier Utility, Water Quality Management, and Safety Considerations – A Review

Abstract Chitosan, a natural polysaccharide derived from chitin, and its nanoparticles have garnered significant attention in the aquaculture industry as functional feed additives. Their positive effects on fish health can be attributed to several key benefits, including enhancing and promoting fish growth, boosting immunity, regulating antioxidant enzyme activities, reducing water pollution, and decreasing lipid peroxidation. However, the cytotoxicity of chitosan nanoparticles (CNPs) remains under evaluation, with results still being inconsistent. Several studies have demonstrated toxic effects in zebrafish and cell lines, leading to decreased hatching rates, increased mortality, and developmental defects. Conversely, alternative studies have proposed that CNPs are non-toxic and suitable for drug delivery. The toxicity of nanomaterials can be influenced by several factors such as nanoparticle size, shape, and electrokinetic potential, rather than their chemical composition or biodegradability. In this review article, our objective is to address the information gap concerning the safe use of chitosan and its derivatives, as well as to resolve discrepancies in results regarding their potential application in the aquaculture industry.