In the present study, immunohistochemical and morphometric analysis was used to characterize variations in muscle growth performance during muscle ¢bre recruitment and hypertrophy. As in ¢sheries, ¢sh were classi¢ed into four age stages: alevin 35 days (0.65 AE 0.08 g); juvenile 60 days (13.67 AE 1.35 g); adult 90 days (73.18 AE 4.70 g) and adult 190 days (349.76 AE 34.62 g). The number of nuclei expressing MyoD and myogenin was similar in alevin, juvenile and adult 90 days; however, in adult 190 days, the number of nuclei expressing myogenin was higher than the number expressing MyoD. The number of proliferating cell nuclear antigen-stained nuclei in each stage was higher than MyoD and myogenin staining with peaks in alevin and adult 90 days. These data suggest that growth per se stimulated cellular proliferation and nuclei accretion of Nile tilapia muscle ¢bres in alevin, juvenile and adult 90 days. Muscle ¢bre di¡erentiation was more pronounced in adult 190 days.

This research was carried out to compare the effect of phytase on performance, in the incorporation and excretion phosphorus in Nile tilápia. Four diets were used: one standard (contol), composed by 3,200 DE kcal ED/kg of ration and 30.0% CP and supplemented with phosphorus (4.0% of dicalcium phosphate), considering the treatment control, and others three, without phosphorus supplementation, with different phytase levels (1,000, 1,500, and 2,000 uf/kg), with four replication, per a period of 82 days. Circular tanks of fiber glass, with constant flow and aeration were used. The results demonstrated that the use of phytase in diets for fish production can reduce the levels of inorganic phosphorus in the diets and minimizing the impacts caused by phosphorus in the production system and in the natural environment and also can improve the productivity, increasing the amount of feed to be supplied and, consequently, facilitating the increase of biomass of fish to be used per production area.

The aim of this study was to analyze the sedimentation rates of suspended material and to estimate the lifetime of the Cachoeira de Cima reservoir, in Mogi Guaçu municipality, Sao Paulo State. Sedimentation chambers were used to collect samples of suspended material. Sedimentation rates for total suspended material (TSM) ranged between 0.27 and 40.70 mg cm -2 d, for inorganic suspended material (ISM), between 0.05 and 34.19 mg cm -2 d, and organic suspended material (OSM), between 0.18 and 6.52 mg cm -2 d. Sedimentation rates of TMS, IMS and OMS at the Cachoeira de Cima reservoir are higher in the rainy season. The lifetime of the reservoir is estimated at 75 years.