Abstract: An experiment to assess the effect of fertilizer (nitrophos) on the growth rate of culturable carps viz., Catla catla, Labeo rohita and Cirrhinus mrigala was conducted in two earthen ponds. Average weight gain in control pond was 80.2, 106.6, 126.1 gm for three fish species, while the weight gain in treated pond was 310, 327.3 and 403.4 gm, respectively. Net fish production in treated and control pond was computed to be 296.3 and 950.0 kg ha–1, respectively. Treated pond showed 3.30 times higher net fish production than the control pond.