Aquaculture contributes to over 70% of Inland fish production placing India to second rank in the world aquaculture produce marking the era for Blue Revolution. Seed availability is the primary requirement of any aquaculture programme. Due to spread of fish and shellfish aquaculture in this country, the demand for seed by aquafarmers has been increased tremendously during the last two decades and there is a need to evolve cheap and reliable technique for controlled seed production. Reproduction in fish and shellfish is predominantly a periodic phenomenon governed by the interplay of a number of endogenous (hormones) and exogenous factors (photoperiod, temperature, rainfall etc). The basic hormonal mechanisms involved in gonadal maturation, breeding (spawning) and seed production of the commercially important fish and shellfish inhabiting Indian waters are being addressed in this book keeping in view of the recent advances in the respective field. Attempts have been made to understand the role played by the hypothalamic hormones (GnRH, GnRIH), Gonadotropins (GtH-1, GtH-2), growth hormone, sex steroids, pheromones, melatonin, vitellogenin as well as secretions from eyestalk, brain and thoracic ganglia in fish and shellfish reproduction, respectively. Hatchery technology for controlled breeding, larval rearing and seed production of Indian major carps, catfish, endangered mahseer and freshwater giant as well as Ganga river prawn (Macrobrachium spp.) have been described. Importance of nutrition in broodstock management for advancing maturity and multiple breeding for enhanced seed production has been elaborated. Isolation, purification and characterization of growth hormone, cryopreservation of milt of the Indian major carps in bulk, calcium metabolism during reproduction, anti-oxidative defense systems, aflatoxin B1 induced pathophysiological changes on ovarian tissues, effects of adreno-cortical hormones and ACTH on hematological parameters, biotechnological applications of hormones and potential scope of transgenic fish and shellfish in enhancing aquaculture production have also been highlighted by the leading scientists.