Aquaculture wastewater management in Nigeria's fisheries industry for sustainable aquaculture practices

Environmental pollution arising from aquaculture wastewater is becoming increasingly important in Nigeria as the aquaculture industry continues to grow to meet the animal protein needs of the country and alleviate its food insecurity crisis. This increase in the number of fish farms in the country, coupled with a concomitant rise in aquaculture wastewater, comes at a cost. The vital components of aquaculture wastewater are remains of unconsumed feed, sediment materials, and metabolic waste of the cultured fish species. These constituents vary in physico-chemistry, volume, composition, and microbial load depending on the type of culture system practiced. Some of the negative effects of releasing aquaculture wastewater into aquatic environments are eutrophication of receiving water, food poisoning, freshwater pollution, bioaccumulation of metals by aquatic biota, increase in the prevalence of diseases among contaminated ecosystem inhabitants, and, in extreme situations, the loss of commercially valuable and viable aquatic resources. Several technologies have been developed to treat aquaculture wastewater and they include: constructed wetlands, recirculatory aquaculture systems, phytoremediation, nanotechnology, as well as physical and biological processes. These methods vary in efficacy, cost-effectiveness, sophistication, and eco-friendliness. A few of the suggested management and policy options to mitigate the impacts of aquaculture wastewater on the environment are improvements in feed quality and feeding methods and government intervention through her agencies. This review suggests a tripod aquaculture wastewater management plan that involves fish farmers, government agencies, and research institutions such that aquaculture wastewaters are treated before getting discharged into inland water bodies, government agencies ensure that fish farmers comply with policies and regulations on waste management, and research institutions develop improved and cost-effective local technologies to treat aquaculture wastewater.