<p>Collagen obtained from the fishing industry is a promising alternative source that utilizes by-products, representing a sustainable strategy for exploiting waste and raw materials within a circular economy. Numerous reviews have compiled data on the methodology of marine collagen extraction, its application, as well as market and future prospects. However, this information is scattered across various publications, providing also an incomplete picture of the geographical distribution of the research and the species used. Therefore, the aim of this review is to conduct a systematic search to compile all relevant information. Additionally, we emphasize update legislation, providing recommendations, and offering future perspectives. The analysis showed that the majority of studies (72%) were conducted in Asia, primarily in China, followed by Europe and South America. Almost 60% of the species studied are marine, followed by aquaculture ones. The studies cover a wide geographical area, mainly focusing on species under high fishing pressure, needing sustainable management measures. Of the traditional extraction methods, enzymatic extraction produces the best results. However, this method is time- and energy-consuming. Green alternatives using supercritical fluids and deep eutectic solvents have emerged, with the expectation of reducing extraction times and higher yields. Further development is crucial for industrial-level exploitation, addressing economic challenges. Collagen is used in a wide range of products, with dietary supplements being its main application, particularly in view of the aging population. Meanwhile, the global collagen market is expected to continue growing exponentially while legislation lags behind, failing to adapt to developments.</p>