3. Results
Water quality parameters were maintained within the range recommended by Vega and de la Cruz (1988) for the species. Dissolved oxygen was 7.25 ± 0.25 mg l− 1, temperature was maintained at 28.5 ± 0.5 °C, and pH was 8.25 ± 0.05. NH4–N had a range between 0.013 + 0.005 mg l− 1.
There were no significant differences in final length up to 75% substitution. However, a regression analysis showed that there was a significant relationship between mean FL and percent substitution (Fig. 1, P