Grass carp growth performance in ponds was compared with two isonitrogenous feeds with different energy and fiber levels. One feed was the standard ASA/China 32/6 freshwater carp growout feed. This feed was formulated to contain 32% crude protein, 6% fat and 2.7% fiber, with dehulled soybean meal as the primary protein source. The second feed was a new ASA 32/3 grass carp growout feed formulated to contain 32% crude protein, 3% fat and 8% fiber, with standard soybean meal as the primary protein source and soy hulls as the fiber source. Both feeds were fed in extruded, floating pellet form to grass carp in a 6-month pond trial at the Xu Xing Zhuang Fish Culture Farm in Beijing. Grass carp fed the ASA 32/6 carp growout feed grew from 100 g to 825 g in 174 days with an FCR of 1.23:1. Grass carp fed the ASA 32/3 grass carp feed grew from 100 g to 815 g in 174 days with an FCR of 1.27:1. Fish growth was significantly different with the two feeds (P<0.05), but there was no significant difference in FCR (P>0.05). Gross production with the 32/6 carp growout feed was 513.7 kg/mu (7,706 kg/ha) for grass carp and 136.1 kg/mu (2,042 kg/ha) for silver carp. Gross production with the 32/3 grass carp feed was 502.3 kg/mu (7,535 kg/ha) for grass carp and 139.0 kg/mu (2,085 kg/ha) for silver carp. The ratio of fed grass carp to filter feeding silver carp was 79/21 and 78/22 for the 32/6 and 32/3 feeds, respectively. Net income per mu was RMB 871 for the 32/6 feed and RMB 1,068 for the 32/3 feed. Return on investment (ROI) was 23.9% with the 32/6 feed and 31.7% with the 32/3 feed. Net income per mu was 22.6% higher and ROI 32.6% higher with the low-fat, high- fiber 32/3 grass carp feed than with the 32/6 carp growout feed because of the significantly lower cost of the 32/3 feed.