Qualidade da água em canais de irrigação com cultivo intensivo de tilápia nilótica (Oreochromis nilóticus)

-1 ; ortofosfato: 0,00 a 0,07 mg L -1 e clorofi la a: 0,00 a 3,36 µg L -1 . Os dados indicam que a criacao de tilapia nilotica, em qualquer das densidades testadas, nao alterou de forma negativa a qualidade da agua do canal, sendo esse fato favorecido pelo manejo de bombeamento e vazao da agua para a irrigacao. Ha, assim, possibilidade de integrar a piscicultura com a agricultura irrigada, maximizando o uso dos recursos hidricos continentais. Palavras-chave - Piscicultura em canais. Limnologia de canais de irrigacao. Piscicultura integrada. Abstract - To evaluate water quality in an integrated cultivation system of agriculture and fi shculture, physical, chemical and biological parameters of the water of irrigation channels stocked with nile tilapia (Oreochromis niloticus) in the density 10; 20 and 30 fi sh/m³, were determined. The experiment was realized in tertiary irrigation channels of DITALPI/DNOCS, sectioned with screens, stocked with fi sh weghing 30±3 g in average, and the water monitored at 8; 14; 21; 28; 35; 43; 50; 58 and 78 days after the start of the experiment. The results of the analysis ranged from 29 to 30.9 oC for water temperature; from 41 to 78 cm for transparency;: from 19.5 to 28.7 mg L -1 for total alkalinity; pH: 6.6 to 7.9; hardness: 26 to 66 mg L -1 ; dissolved oxygen: 4.3 to 6.9 mg L -1 ; electrical conductivity: 0.059 to 0.150 mS cm -1 ; carbonic gas: 3.4 to 5.3 mg L -1 ; nitrite: 1.93 to 3.36 mg L -1 ; ortophosphate: 0.00 to 0.07 mg L -1 and chlorophyll ": 0.00 to 3.36 µg L -1 . The results indicated that raising tilapia in the channels, for the tested densities, didn't alter in a negative way the quality of the water for irrigation. In conclusion, there is the possibility of integrating the fi sh farming with the irrigated agriculture, maximizing the use of water resources.