A study on the culture of grass carp, Ctenopharyngodon idellus with Aristichthys nobilis was conducted at the of Freshwater Fish Research Centre (FFRC), Batu Berendam, Melaka. The stocking density of grass carp was as follows: 250, 1,250, 2,500 and 3,750/ha. The stocking density of bighead carp remained constant at 2,500/ha. The stocking ratio of 1,250 grass carps to 2,500 bighead carps produced the maximum harvest of 1,178.75 kg/ha/8 months. However, there was no significant difference (P > 0.05) between those treatments. The highest production ratio for every kg of grass carp was 2.33 kg of bighead carp. Nevertheless, the increase or decrease in stocking density of grass carp did not affect the final production of bighead carp or the total fish biomass. There is a significant difference (P < 0.05) in terms of the mean individual final weight of grass carp and bighead, the final production of bighead and the survival rate of grass carp. The mean yield of bighead remained constant, in the region of 1,000 kg/ha irrespective of the stocking density of grass carp in the extensive culture system.