Three major carp species, viz. catla Catla, Labeo rohita and mrigal Cirrhinus mrigala, are farmed in polyculture systems in the southern state of Andhra Pradesh, India. A survey of 189 carp farms was undertaken, and principal component analysis was used to assess the relationships between farm inputs and fish yield. Model results exhibited a strong relationship of yield with the stocking density of all three major carp species.