This study aimed to evaluate the resistance to stress (transport, thermal, and osmotic) and growth performance of Nile Tilapia Oreochromis niloticus post‐larvae fed a diet supplemented with Yeast Saccharomyces cerevisiae. Two groups were established in triplicate: fish fed a diet supplemented with probiotic and control group without probiotic. Two hundred larvae per experimental unit were randomly distributed. Fish were fed 6 times daily. After 20 days, growth performance was determined, including survival, final weight, specific growth rate, feed conversion ratio, and effectiveness of sexual reversal. From these fish, 30 fingerlings (average weight 0,25 ± 0.02 g) per experimental unit were removed to perform stress tests (n=180), with 10 fingerlings being subjected to different stressors (i.e., transport, osmotic shock, and thermal shock). Fish fed with probiotic showed improved performance in final weight (16.6%) and survival (15.1%), as well as higher resistance to thermal (102.3%) and osmotic challenge (27.5%) compared to control fish. In addition to improved growth and survival performance, probiotic supplementation had no effect on the rate of masculinization.

The objective of this study was to evaluate the productive performance, organosomatic indices and liver-intestinal histomorphometric parameters of Nile tilapia (Oreochromis niloticus) juveniles, fed diets containing probiotics (yeast - Saccharomyces cerevisiae) and reared at different densities of storage. In this experiment, 450 juveniles of tilapia (2.9 ± 0.23 g) were distributed in 18 experimental units arranged in RAS and arranged in a randomized block design in a 2x3 factorial scheme. These animals were fed two diets, the first without yeast and the second containing 0.1% yeast inclusion and distributed in three stocking densities of 15, 25 and 35 fish / m3 (500, 833 and 1166 fish / m3). There was an improvement in the oxygenation of the medium with the use of yeast, as well as in the lowest stocking densities evaluated (15 and 25 fish / m³). However, lower specific growth rates and higher viscerosomatic index were observed in animals supplemented with 0.1% yeast. For the average area of hepatocytes, there was an interaction between the evaluated factors (use of probiotic x storage density), where the best values were found in the lowest storage densities (15 and 25 fish / m³), regardless of use or not of the probiotic. It is recommended to use a stocking density of 15 to 25 fish / m³ and a supplementation of 0.1% with yeast as a probiotic, in order to improve liver health and oxygenation of the water used to grow Nile tilapia juveniles cultivated in RAS.