Mortality was verified when the bags were opened and samples
of 5 fingerlings were collected from each treatment to measure body Na+ and K+ levels. These fishes were sacrificed, weighed, immersed
individually in hydrochloric acid, and left to dissolve in an oven at
80_C for 24 hours, according to the method of Ogner (1983). The Na+
and K+ levels of these solutions were measured with a B262 flame
spectrophotometer (Micronal, Sáo Paulo, SP, Brazil; precision