The effectiveness of pressmud, a sugarcane by-product, was tested as a manure in the production of natural food and carp, by conducting two experiments. The first experiment, of 5 weeks duration, examined the effect of pressmud addition on water quality and natural food production. This study was carried out in fibreglass tubs (1.54 m(3)) with a 5 cm mud layer, employing pressmud at dosages of 5000, 10,000 and 15,000 kg ha-(1) for treatments T-1, T-2 and T-3, respectively. Unfertilized tubs served as control (To). The second experiment of 120-day duration to study the effect on growth, survival and quality of common carp was conducted in 25 m(2) cement tanks with 15 cm-mud bottom, using the same dosages of pressmud. The control tanks in this experiment were manured with cattle dung at 10,000 kg ha(-1) (TO). Application of pressmud enhanced (P < 0.05) natural food production, with the greatest effect noted in treatment T3. Fish growth was significantly greater (P < 0.05) in treatments T-2 and T-3, there being no difference in growth between the control (TO) and 5000 kg pressmud treatment (T-1). The greatest survival and production were obtained under treatment T-2, which indicates that the dosage of 10,000 kg ha(-1) pressmud is optimal for carp culture. A significant effect (P < 0.05) of pressmud on carcass protein was observed. Organoleptic quality of both raw flesh and cooked meat of carp was not affected (P < 0.05) by pressmud treatment. (c) 2005 Elsevier Ltd. All rights reserved.