The production of fish in floating net cages increased in Brazil during the last decade. The low cost of cage construction and the enormous area of impounded water in Brazil have attracted interest to this activity. The objective of this research was to provide information on the effect of stocking density on the growth and yield of Florida red tilapia, reared in floating net cages. Twelve floating, 5-m3 net cages located in an 1-ha reservoir were stocked with 25, 50, 75 and 100 sex-reversed Florida red tilapias/m3. Fish were fed 32 and 28% crude protein commercial floating diets for 253 days. Maximum, minimum and average water temperatures were 32.2; 16.0 and 23.9 OC, respectively. Average conductivity (58 mS.cm-2), total alkalinity (28 mg/L), un-ionized ammonia (0.26 mg/L), nitrite (0.02 mg/L), dissolved oxygen (DO = 4.1 mg/L), pH (7.3) and water transparency (37 cm) were recorded. Final average body weight (W = 279.54 g), standard length (L = 18.72 cm), condition factor (K = 4.12), feed conversion rate (3.15), survival rate (96.9%), mean daily weight gain (0.92 g/day), specific growth rate (0.70 %/day) and coefficient of variation of W (0.357), L (0.136) and K (0.136) were determined. No significant effects (P>0.05) of stocking density were observed on these parameters. Stocking density of 100 fish/m3 yielded the highest biomass per m3 (P<0.001).
stocking density; cage; red tilapia