The study aimed to process and characterize acid silage from the residues of two species of Amazonian fish, piramutaba (Brachyplatystoma vaillantii) and dourada (Brachyplatystoma rousseauxii), in four storage times, with a view to use in animal feed. The research was developed at the Food Laboratory of the Center for Nature Science and Technology (CCNT) at the State University of Pará (UEPA). The physical-chemical analyzes (moisture, ash, proteins and lipids) of the wet silages and defatted flours were performed in triplicate considering four storage times: after the addition of acid (T0), on the seventh day of silage (T7), in the fifteenth day (T15) and on the twentieth day (T20). The data were submitted to analysis of variance (ANOVA) and the means compared by Tukey's method (α = 0.05). On the 7th day, the pH stabilized at 4.3 for the two silages. During the experimental period, the temperature in the dourada silage varied between 25.5 and 28.0 ºC, and in the piramutaba silage between 25.0 and 28.0 ºC. The lowest humidity values for the silage of bream and piramutaba were 75.69% (7th day) and 73.66% (15th day), respectively. Higher ash values were observed, on the 20th experimental day, for dourada (4.15%) and piramutaba (3.77%). The dourada silage, on the 7th day, showed a higher average protein value (13.10%), and the piramutaba, on the 15th day, with a value of 12.86%. The flours of dourada and piramutaba presented protein values of 66.78% and 66.64% and lipids of 6.85% and 9.05%, respectively. The defatted piramutaba flour showed higher values (1.75%) of lipids compared to the golden flour (1.11%). Therefore, the use of dourada and piramutaba residues showed excellent nutritional potential for use in animal feed, with an excellent level of protein and low values of humidity and lipids.