This work was carried out on. "mandi" (Pimelodus danas Bloch) a specie of catfish from Piracicaba river, in São Paulo State, Brazil, with the purpose of knowing its chemical composition and some informations of its nutritional value. The fishes picked out in June and July, showed the following composition of the edible part: moisture 72.02 g/100 g, protein 17.93 g/100 g, lipids 9.00 g/100 g, ash 1.12 g/100 g, calcium 94.13 mg/100 g, total phosphorus 550.15 mg/100 g, inorganic phosphorus 262.93 mg/100 g, iron 7.41 mg/100 g, sodium chloride 0.30 g/100 g, vitamin A 120.10 U.I./g lipids and pH 6.80. It was showed that each 100 g of the fish flesh can supply about 12% of total phosphorus, 69% of iron, 22% of vitamin A and 28% of the caloric daily needs.