The application of nanotechnology in aquaculture for developing efficient vaccines has shown great potential in recent years. Nanovaccination, which involves encapsulating antigens of fish pathogens in various polymeric materials and nanoparticles, can afford protection to the antigens and a sustained release of the molecule. Oral administration of nanoparticles would be a convenient and cost-effective method for delivering vaccines in aquaculture while eliminating the need for stressful, labour-intensive injectables. The small size of nanoparticles allows them to overcome the degradative digestive enzymes and help deliver antigens to the target site of the fish more effectively. This targeted-delivery approach would help trigger cellular and humoral immune responses more efficiently, thereby enhancing the protective efficacy of vaccines. This is particularly relevant for combating diseases caused by pathogens like Aeromonas hydrophila, a major fish pathogen responsible for significant morbidity and mortality in the aquaculture sector. While the use of nanoparticle-based vaccines in aquaculture has shown promise, concerns exist about the potential toxicity associated with certain types of nanoparticles. Some nanoparticles have been found to exhibit varying degrees of toxicity, and their safety profiles need to be thoroughly assessed before widespread application. The introduction of nanovaccines has opened new vistas for improving aquaculture healthcare, but must be evaluated for potential toxicity before aquaculture applications. Details of nanovaccines and their mode of action, with a focus on protecting fish from infections and outbreaks caused by the ubiquitous opportunistic pathogen A. hydrophila, are reviewed here.

In this study, chemiluminescence (CL) from oxidation of formaldehyde and luminol was investigated under alkaline conditions to develop a sensitive analytical tool for formaldehyde detection. The developed method was successfully applied for detection of formaldehyde in spiked soft drinks, wine, and raw fish storing solution. CL enhancement by optimized conditions of luminol, urea–H₂O₂, pH, and sequence of addition was investigated, which was not explored previously. The limit of detection was 10 pg ml⁻¹ and linear range 10 pg ml⁻¹ to 100 μg ml⁻¹ with a regression coefficient of R² = 0.998. The importance of these experimental parameters is discussed based on knowledge of oxidation of luminol by urea–H₂O₂ and further enhancement of CL by formaldehyde oxidation. Formaldehyde was spiked and recovered with 95–99.9%. The results obtained were compared with those of high-performance liquid chromatography (HPLC) and were well correlated.