Energy and Resource Conversion of Fish Waste: Current Status and Future Prospects

The global fish industry is an essential contributor to food security and the economy; however, it produces considerable quantities of fish waste. Depending on species and processing methods, 20–80% of fish biomass is discarded as waste, amounting to almost 64 million tons annually. Conventional disposal methods such as landfilling, incineration, and wastewater discharge cause environmental pollution and greenhouse gas emissions. Therefore, for sustainable development, it is important to valorize fish waste into renewable energy and value-added products. Hence, this review aims to encourage the technical development of fish waste into bioenergy and bioresources by thoroughly studying key technologies for converting it into biogas, biodiesel, fertilizer, animal feed, and biochar. Although several studies have explored these technologies, most remain disjointed and lack a systematic assessment. Therefore, this work attempted to critically evaluate the technological principles, advantages, limitations, and optimization strategies of current valorization approaches. Furthermore, several recommendations have been proposed, including conducting pilot-scale trials, producing higher value-added products within a biorefinery system. Overall, this review provides a holistic outlook on the energy and resource conversion of fish waste, supporting sustainable waste management.