Grass carp were grown from fry to fingerlings on two feed regimes using the ASA 80:20 production model and soy-based feeds. Grass carp grew from 0.3 g to 83 g when fed a 36% protein, soy-based diet for the entire production season. Grass carp grew from 0.3 g to 78 g when fed a 36% protein, soy-based diet to size 25 g, followed by feeding with a 32% protein, soy-based diet thereafter. Growth was significantly different with the two feed regimes. FCR for the 36% protein feed regime was 1.12:1 for the 121-day feeding period. FCR for the combination feed regime was 1.19:1. No economic benefit was obtained by reducing the protein content of the feed once grass carp reached 25g in weight. The reduction in feed cost obtained with the combination feed regime was offset by the better growth performance of fish receiving the 36% protein feed for the duration of the production season.