Bioplastics produced from residual marine biomass (like fish scales and prawn shells) are a sustainable alternative to traditional plastics and contribute to the circular economy. Key biopolymers are chitosan, valued for its nontoxicity and film-forming ability, and gelatin, which in turn can be efficiently extracted from fish waste at up to 58.25%. The mechanical properties of these materials can be engineered for strength and flexibility: for example, chitosan films can be chemically tuned, while reinforcement with cellulose nanocrystals (CNCs) can achieve enhanced tensile strength to values as high as 27.64 MPa. Derived from the sea, these bioplastics also show fast biodegradability; studies report up to 85% degradation in 14 days and between 71-84% of biodegradation in soil within 21 days. Furthermore, their functionality goes beyond passive packaging, incorporating natural extracts with active protection of foods. Gelatin films with fig leaf extract exhibited excellent antioxidant and antibacterial activity. On the other hand, chitosan films enriched with Borago officinalis extract can extend the shelf life of rainbow trout by six days. These findings underlined the large potential of marine waste as a source of eco-friendly, highperformance bioplastic packaging for the food industry.