Cattle-dung-based biogas-plant effluent was evaluated as a dietary ingredient in pelleted feed in place of rice bran for tilapia culture over a period of 42 days. The mean growth rare of fish (0.032 g individual(-1) day(-1)) and muscle protein (39.28 mg 100 mg(-1)) showed no change when the biogas-plant effluent was used. It is recommended that dried biogas-plant effluent could take the place of rice bran in pelleted fish feed. Copyright (C) 1997 Elsevier Science Ltd.