This authored book is focused on SDG 14: Life below water, comprehensively addressing all facets of biotechnology and bioinformatics related to fisheries. It offers an extensive exploration of the detail on structure, function and types of nucleic acids, concepts of gene and genetic code, mutations, and their implications. The book provides essential information on gene regulation and expression in prokaryotes and eukaryotes. Step-by-step descriptions are provided for technologies such as gene transfer, rDNA, transgenic fish production, animal cell culture, hybridoma technology and cryopreservation technology in fishes. Special emphasis has been given to topics like RNA in gene regulation, epigenetics, and DNA and protein sequencing. Various molecular techniques and markers have been discussed in detail. Further, various topics on bioinformatics including different databases, formats, sequence retrieval, manipulation, analysis, primer design, molecular visualization, genomics,and proteomics are also covered. This volume will prove invaluable to aquaculturists, equipping them with essential techniques and protocols. It constitutes essential reading for students enrolled in aquaculture or fisheries courses within tropical and sub-tropical regions.