Nanotechnology-Based Immunostimulants in Aquaculture: Mechanisms, Advances and Practical Applications

The rapid expansion of aquaculture has intensified disease outbreaks, increasing antibiotic reliance and accelerating antimicrobial resistance (AMR). Given the ecological and economic consequences of traditional treatments, nanotechnology-based eco-efficient alternatives are urgently needed.

The primary goal of this manuscript is to critically evaluate the practical applicability, mechanisms of action and safety profiles of nano-immunostimulants in aquaculture. Furthermore, this review aims to provide a comparative roadmap of major nano-delivery systems (polymeric, metallic, lipid and carbon-based), identifying their safety-efficacy trade-offs to facilitate their transition from laboratory research to commercial aquaculture.

A structured literature search was conducted across major databases (PubMed, Scopus, Web of Science and ScienceDirect) targeting nano-immunostimulants, delivery systems, fish/shellfish immunity and environmental safety. Due to high methodological heterogeneity, data were synthesised qualitatively.

Polymeric nanocarriers (e.g., chitosan, alginate, PLGA) show the highest translational potential, significantly improving immune biomarkers, bioavailability and survival against major pathogens (e.g., Aeromonas and Vibrio spp.) with favourable safety profiles. While metallic, lipid and carbon-based nanomaterials exhibit strong immunomodulatory and antimicrobial potential, their practical adoption is currently constrained by variable toxicity, environmental persistence and bioaccumulation risks.

Nano-immunostimulants represent a transformative strategy for antibiotic-free, One Health-oriented aquaculture. To achieve commercial viability, future research must shift from basic efficacy trials towards green synthesis, standardised ecotoxicological assessments and field-scale cost‒benefit validation.