Extraction and Utilization of Chitin and Chitosan from Waste Yields of Economically Important Crustaceans and Molluscs for Improved Fish Production

Background: Every year, about eight million tons of different species of crustacean shells are produced, with several million tons of various mollusc shells world-wide. These shell wastes are usually disposed into the water body or mainland, littered everywhere, with significant impact on the environment. Aim: To provide a profitable way of reducing and possibly removing shell wastes, and harness them for a better purpose through an eco-friendly and sustainable technological approach. Main Body of the Abstract: This review underscores a broad list of economically important crustaceans and molluscs, harvestable in Nigeria coastal waters whose shells usually ended up as wastes. Chitin, being the primary component of these wastes can be extracted and deacetylated into chitosan, or synthesized into nanoparticles for better applications in various aspects of aquaculture. Both chemical and biological methods of chitin extraction were discussed, however, bioextraction method was recommended due to its eco-friendliness, biocompatibility, and non-hazardousness. Various ways by which these shell wastes can be processed and utilized for improve aquaculture practices were also discussed. These include fish growth enhancement, pond water treatment, as antioxidant, as immuno-stimulant, as antimicrobial, as drug carrier, and several other purposes. Conclusion: There are much hidden wealth in these fisheries by-products (Crustacean and Mollusc shells) if properly valorized. It has a great potential to transform aquaculture industry, and bring significant, and sustainable economic development in Nigeria.