Quality seed, feed and fertilizer are known to decree target fish yield in any type of aquaculture system. Among these vital factors, the right type and input schedule of fertilizers have gathered much scientific concern. Obviously, phosphorus the major limiting nutrient of freshwater culture system has been studied in detail by various workers. However, there is brevity of information on the colossal loss of money encountered by the fisheries sector engrossed in freshwater culture due to the transformation of phosphatic fertilizers into non-recyclable apatite phosphorus. This book provides the first hand information on the utilization of sodium tripolyphosphate in hard water fish culture system for relegating the formation of apatite. The merit of such investigations lie in the fact that the development of a proper phosphatic fertilization schedule for hard water will hold good for brackishwater fish pond also. The results of the present investigation affirm the fact that apatite occurs as the second major constituent of total sedimentary phosphorus. Though the chemical reactions leading to the formation of apatite in aquatic ecosystems remain as a riddle, many of the field trials fortify the operation of the phenomenon of apatite formation in aquaculture system. The present study focuses its prime attention over this crucial reality and advocates the benefits of utilizing sodium tripolyphosphate as a phosphatic fertilizer in aquaculture system. The authors are convinced that intensive field trails in this regard would pave way for the most aspired blue revolution. Contents: Chapter 1: Introduction, Chapter 2: Sample Collection and Methods; Field Experiments on the Dynamics of N and P, Experiment on Regeneration of Sedimentary Nutrients, Experiment on the Hydrolysis of Polyphosphate, Chapter 3: Salient Physico-Chemical Characteristics of the Experimental Ponds; Results, Water Temperature, Secchi Disc Regarding, pH, Dissolved Oxygen, Water Hardness, Carbonate Alkalinity, Bicarbonate Alkalinity, Chlorphyll a , Net Productivity, Assimilation Number, Discussion, Chapter 4: Nitrogen Cycle, Chapter 5: Chemical Species of Nitrogen in Water and Sediment; Results, Ammonia-N, Nitrite-N, Nitrate-N, Exchangeable Ammonia-N (E-NH3-N), Exchangeable Nitrite-N (E-NO2-N), Exchangeable Nitrite-N (E-NO3-N), Sedimentary Organic Nitrogen (SON), Discussion, Chapter 6: Phosphorus Cycle, Chapter 7: Chemical Species of Phosphorus in Water and Sediment; Results, Soluble Inorganic Phosphorus (SIP), Soluble Organic Phosphorus (SOP), Particulate Phosphorus (PP), Polyphosphate-P (PyP), Neutral Hydrolysable Phosphorus (NH-P), Phosphorus Bound to Carbonate (CO3-P), Phosphorus Bound to Oxides of Iron and Manganese (O-Fe and Mn-P), Phosphorus Bound to Iron and Aluminium (Fe and Al-P), Apatite Phosphorus (A-P), Phosphorus Bound to Organic Matter (Po), Residual Phosphorus (R-P), Regeneration of Nitrogen and Phosphorus from Sediment, Hydrolysis of Polyphosphate, Nitrogen: Phosphorus Ration, Fish Production, Discussion, Chapter 8: Conclusion.