The advancement of Aquatic Biotechnology has encouraged the use of experimental procedures to improve aquatic animal production. One of the experimental techniques is the protein recombination technique used for this purpose. Recombinant DNA technology is a useful and valuable tool for producing large amounts of protein from different fish species. These proteins can be employed in aquaculture as medicines, vaccinations, diagnostic reagents, and for sexual maturation enhancement. Recombinant proteins for these usages will primarily be produced in the laboratory using prokaryotic and eukaryotic expression host systems such as mammalian cells, bacteria, yeast, transgenic plants, and insect cells. There are many molecular tools and protocols, such as extensive catalogs of expression plasmids, a large number of genetically engineered species, and culture strategies, for high-level production of recombinant proteins. Advances in the production of recombinant proteins have reversed previous trends, leading to much better efficiencies and lower costs. Furthermore, these breakthroughs enabled the industrial synthesis of such proteins, paving the way for the diagnosis and treatment of a variety of diseases and disorders, as well as the development of off-season breeding programs. This review covers some key findings from the recent studies concerning to employment of recombinant proteins in fish to introduce the application and importance of recombinant proteins in aquaculture.