Being an essential component of the world's economy and nourishment, fish aquaculture is at risk due to improper resource management, environmental damage, and climate change. Fish side streams are an intriguing resource and treasure trove of numerous healthful and physiologically active molecules, which have the potential to significantly contribute to the production of essential components for pharmaceutical, electrical, optical, biotechnological, functional, and nutritional compounds. The practical application of these bioactive compounds has encouraged research into sustainable extraction methods to optimize the recovery process. The present chapter highlights a thorough description of research performed considering extracting valuable compounds from fish waste. Integrating proteins, and bioactive substances from the muscles, tissues and fibers from the scales and pomace increased food items’ nutritional content and applicability. Phenolic molecules, carotenoids, and other bioactive substances in fish demonstrated excellent antioxidant, antimicrobial, hypoglycaemic, and anticancer properties, suggesting good potential utilising in pharmaceutical products. Finally, the main possibilities and critical challenges, as well as recent developments, are described for practical usage of these compounds for reducing the adverse impacts of food waste and to improve the circular economy.