The aim of this work was to evaluate the influence of Trichlorfon on the growth of cultured fishes. Using Oreochromis niloticus as fish model, bioassays were performed in the laboratory and field. Biometry was performed for 16 weeks. The treatment started after the sixth week of biometry, with the application of five weekly doses of 0.25 ppm of Trichlorfon. Growth data were compared by longitudinal analyses. In the laboratory, the treated fishes showed a reduction of growth; however, the statistical significance was only seen in the variable weight. In the field, the growth of treated fish was higher than that of the controls. This suggested that the treatment should be done in tanks with lower relative biomass to maintain the good zootechnic characteristics of fishes.
Organophosphate; Tilapia, and aquaculture
