CALCIUM SILICATE AND SOIL IN THE INTENSIVE CULTIVATION OF NILE TILAPIA

Abstract

This study aimed to analyze the calcium silicate and soil, comparing them to conventional liming products and verifying their effects on the stability of the environment and development of tilapia juveniles. For 60 days, juveniles were cultivated under five conditions, namely: Control - aquarium containing only water; Calcites – water and calcium carbonate – CaCO₃; Dolomitic - water and dolomitic limestone - 70% CaCO₃• 30% MgCO₃; Soil – aquarium with soil at the bottom and Silicate – water and calcium silicate – Ca?SiO? (3 g of salts L^-1), with five repetitions each. The measured parameters were conductivity, pH, redox potential, salinity, turbidity, ammonia, nitrite, nitrate, alkalinity, hardness, calcium, magnesium, silica, weight, standard length, total length, biomass, and survival. From the records, weight gain, biomass gain, feed conversion ratio, and Fulton's condition factor were calculated. The calcium silicate presented better results (total length and weight gain) than those observed in the soil, and equivalents (survival, individual consumption, weight, weight gain, biomass, standard and total lengths, and feed conversion) to calcitic and dolomite limestone. The pH presented better results for the silicate and was similar to the calcitic treatment, which did not differ from the dolomite. Alkalinity and silica had higher values in the silicate. Hardness and calcium presented higher values in the silicate and in the calcitic treatments when compared to the control and the soil. Calcium silicate is a viable and recommended alternative liming in the intensive cultivation of juvenile Nile tilapia. He presented results equivalent to calcitic and dolomitic limestones, traditional salts for this practice. Calcitic and dolomitic limestones proved to be efficient in the liming process, in the intensive system. The use of soil as a liming material did not show promising results. However, it, like other products, should be better evaluated.