Ingredients used for fish nutrition aim to provide nutrients to meet their performance requirement, so diet digestibility is important. In this scenario, scientists are constantly searching for new ingredients. The use of enzymes for animal feed is common practice nowadays to improve animal performance and nutrients utilization and the use of exogenous microbial enzymes has shown good results. The utilization of microorganism for ingredients pretreatment is also a way of provide a different sources of nutrients, as protein. This study aimed to find the best fungi producer of protease by Solid State Fermentation (SSF) to improve diet nutritional availability. Enzyme production was prepared by Solid State Fermentation (SSF) using two strains of Aspergillus niger belonging to collection of microorganisms from Microorganisms Laboratory, Department of Chemistry and Biochemistry, UNESP – Botucatu and four fungi strains (A. niger 18 and 65, A. flavipes, A. brasiliensis and Penicillium roqueforti) offered by Osvaldo Cruz Foundation with soybean meal and oat meal as substrate. The enzymatic activity for protease was measured using azocasein as substrate to select the best fungus for enzyme production. Enzyme activity observed for A. flavipes and P. roqueforti using oat meal as substrate was 1,389 and 1,260 U mL-1. Yet, the other strains also showed enzyme activity, besides two strains of A. niger with both substrates. The high protease activity detected for these strains, the ease extraction, added the abundance and low cost, made this microbial protease potential alternatives to commercial exogenous additive enzymes for animal nutrition.