This experimentwas conducted to evaluate increasing levels of mannanoligosaccharides (MOS)in the diet of Nile tilapia larvae (Supreme®) at the sex reversalstage for 30 days. Nile tilapia larvae (n = 1500, p = 0.01 ± 0.001 g),were randomly distributed in 30 tanks of 100 liters each, for 30 days. The fishwere distributed in a randomized design with six treatments and five replicates.The control diet (no MOS) was elaborated to contain approximately 35% of crudeprotein and 3,100 kcal DE/kg. Mannanoligosaccharides were included in the otherdiets, replacing corn, at levels of 0, 0.15, 0.30, 0.45, 0.60 or 0.75%. Linearincrease in the intestine length, intestinal villous height and villi densitywas observed with the dietary MOS increase. No differences in body composition,weight gain, final weight, final length, condition factor, survival rate ornumber of goblet cells of the gut of the larvae were observed. A quadratic effecton feed conversion ratio was observed with the MOS inclusion and the best valuewas estimated with 0.34%. Dietary MOS inclusion at 0.34% improves feed conversionand increases intestine length, villi height and density of intestinal villiin diets for Nile tilapia larvae.
