the experiment with the objective of verify the effects of the processing (extrusion, rolling and pelleting of corn) on the performance and composition of the piaba (leporinus frederici) carcass, was conducted in the usina hidreletrica da companhia energética de minas gerais - cemig (minas gerais hydroelectric station), in the itutinga- mg , with the lenght of 45 days. the experiment was undertaken in 24 cages of 1m3, 480 fingerlings were utilized, they were distributed into blocks. the four experimental rations were formulated based in corn meal, extruded corn, rolled corn and pelleted corn. the data obtained were submitted to the analysis of variance and the comparison of means of the treatments by the scott & knott test. the results showed any statistical difference in the performance parameters. however, the use of extruded corn and corn meal increased protein content (p<0.05) and decreased fat content (p<0.05) of the carcass traits, these results showed, improved protein utilization for structural purposes. in conclusion the corn processing did not improve the performance of the fish and that corn meal and extruded corn increased protein content and reduced fat content in the carcass.