lipid, dry matter (DM), ash and total phosphorus. Feces from the
fourth sampling period were analyzed for phytate-P.
The fish were individually weighed at the end of the digestibility
trial (day 13), and returned to the tanks where they were fed a
fixed daily ration for 12 days corresponding to 1.5% of the biomass
measured at the end of the digestibility trial. This was done to ensure
that the dissolved waste produced (N and P) was generated from a
well defined and constant amount of feed. After the first 5 days of
this period, influent water was turned off for 24 h (and air diffusion
turned on) and the waste produced was measured as the delta increase
derived from water samples collected just prior to feeding at
10:00 and 24 h later, respectively. The procedure was repeated after
72 h (i.e., 3 days) to obtain replicate measures for each tank.