At the end of the 45 days of experiment, significant difference was observed due to the fact that as the final weight and weight gain in the shrimp increased, the percentage of S. platensis in the diet increased, indicating a better outcome in these parameters with percentages of 30 and 40%. However, when compared to the commercial diet, lower results were observed, but with values close to those obtained with 40% supplementation. The literature has shown better results for growth with supplementation of S. platensis up to 25% in the diet for several fish species, but similar or better results compared to this study can be found if the percentage of this microalga is increased in diets (Table 4).
According to Abdel-Tawwab and Ahmad (2009), these positive effects on growth are attributed to nutrient digestibility and high nutritional content present in S. platensis. The mean survival rate of shrimp showed significant difference, and the results were not influenced by the percentage of S. platensis in diets, with high values, which show the positive effects of this microalga to promote better cultivation conditions. Jaime-Ceballos et al. (2007) reported that a 25% increase of these microalgae in the diet of post-larvae Litopenaeus schmitti showed higher growth and survival rates. Ghaeni et al. (2011) used S. platensis in the diet of tiger shrimps Penaeus semisulcatus and obtained better weight gain results. Most researchers have used microalgae to feed fish including tilapia, however, Gomes et al. (2012) and Ungsethaphand et al. (2010) reported greater weight gain efficiency and survival rates.