(Limnological characterization in culture ponds of tilápia Oreochromis niloticus.)

Abstract

Physical and chemical characteristics and chlorophyll a of the water of four culture ponds of tilapia (Oreochromis niloticus) were studied during the period of June/1985 í  April/1986 at the Experimental Fish Station of the Fishery Institute, in Pindamonhangaba. The experiment, in each pond, ended when the mean weight of 500 g (commercial weight) was reached. Four treatments were utilized: T₁) pig manure plus chemical fertilizer; T₂) pig manure plus chemical fertilizer plus ration; T₃) chicken manure plus chemical fertilizer; T₄) chicken manure plus chemical fertilizer plus ration. The mean values of the limnological characteristics studied to the four treatments (T₁, T₂, T₃, T₄) were, respectively, of temperature: 24.8; 23.5; 25.0 and 24°C; pH: 8.0; 8.8; 9.2 and 8.8; electric conductivity: 62.0; 51.6; 79.6 and 60.0 µS/cm; ammonium: 0.57; 0.52; 0.70 and 0.61 mg/L; nitrate: 0.19; 0.16; 0.21 and 0.20 mg/L; phosphate: 0.32; 0.20; 0.28 and 0.17 mg/L; silic: 4.24; 4.26; 3.81 and 5.16 mg/L; dissolved oxygen: 9.56; 9.15; 12.15 and 10.04 mg/L; oxygen saturation: 124; 119; 157 and 116%; chlorophyll a: 70.3; 88.5; 93.2 and 122.9 µg/L. The pond T₂, where the tilapia development was the best one, besides of to show the lowest mean values of temperature, conductivity, ammonium and nitrate, the amplitudes of variation of those parameters were the shortest ones.