Based on a mean FCR of 1.69 for commercial feed with a protein content of 25% and assuming that 30% of the notrogen in the feed is converted into fish flesh, it is estimated (gross) that 47.3 kg nitrogen is discharged per tonne of catfish produced. On this basis,in 2007, when 683,000 tonnes of catfish was produced in the whole of the Mekong Delta, approximately 32,306 tonnes of nitrogen was discharged into the Mekong River.