Using weekly, fortnightly and monthly frequencies, and high (200 kg P 2O 5) and low (100 kg P 2O 5) doses of Mussoorie phosphate rock (MPR) application, the growth response of the carp, Cirrhinus mrigala, was examined in outdoor tanks in triplicate in relation to phosphorus dynamics of water and sediments. Differences in the concentrations of different species of phosphate in water (orthophosphate, total hydrolysable phosphate, total phosphate) and sediment (available phosphate and citrate-soluble phosphate), net primary productivity as well as fish growth were maximum for the weekly system, followed by the fortnightly, and were lowest in the monthly system. Stepwise multiple regression analysis of the data revealed that fish growth regardless of treatment was primarily contributed by net primary productivity (89–97%), orthophosphate level of water (4.5%) and sediment pH (1.4%).