The apparent digestibility coefficients (ADC) of the diets were conducted according to Felix and Brindo (14) , by incorporation of 1% chromic oxides indicator in each diet. Fishes were acclimated to the experimental diets during the first couple of days and no feces were collected. The experiment lasted for three weeks. Diets were given daily at 9:00 am, and one hour after food consumption uneaten feed and feces were removed by siphoning. Feces collected from triplicate treatments on 20-min intervals were pooled, dried by air and stored for further analysis. The amount of chromic oxide present in the feeds and fecal samples was estimated by digestion with concentrated nitric and perchloric acids, and the absorption was measured in the atomic absorption at 357.9 nm. The ADCs were calculated according following equations:
Total apparent digestibility (ADS total) % = 100 -(100 × (% indicator in food/ % indicator in feces))
Nutrient apparent digestibility % = 100 -(100× (% indicator in food/ % indicator in feces) × (% nutrient in feces/ % nutrient in food))