: A Comprehensive Textbook for B.F.Sc. Students is a meticulously crafted academic resource designed to meet the complete requirements of the ICAR Bachelor of Fisheries Science (B.F.Sc.) curriculum . Written in clear, accessible language with technical precision, this book takes the student on a systematic journey through the living ocean — from the sun-drenched coral reefs of the Indian coast to the lightless abyssal plains of the deep sea. Spanning 25 well-structured chapters organized into eight thematic units, the book covers every dimension of marine biology prescribed in the ICAR undergraduate syllabus. Beginning with the physical and chemical properties of the marine environment, the text progressively introduces the extraordinary diversity of marine life — phytoplankton, zooplankton, seaweeds, invertebrates, fishes, reptiles, seabirds, and marine mammals. Dedicated chapters explore the ecology and conservation of India's most important marine ecosystems — coral reefs, mangroves, seagrass beds, estuaries, and the deep sea — with special reference to the Gulf of Mannar, Lakshadweep, Andaman and Nicobar Islands, and the Sundarbans . The book uniquely integrates applied and emerging topics of direct relevance to fisheries science students — marine fisheries management, mariculture, marine biotechnology, ocean remote sensing, climate change impacts, and the blue economy — equipping graduates with the knowledge needed for professional careers in fisheries research, aquaculture, conservation, and ocean governance.