These results support those obtained in a previous study aboutpeptide identification in a shrimp hydrolysate [12]. In that work,808 peptides were identified by ESI-MS/MS and MALDI-TOF/TOFusing Mascot program with the NCBI and a homemade database.The number of identified peptides is 1.7 fold more in the presentstudy. This confirms the efficiency of the present experimentalstrategy based on 2D peptide fractionation (nLC/OFFGEL elec-trophoresis), on the use of complementary mass spectrometers(ESI-MS/MS and MALDI-TOF/TOF), and enhanced by the creationof a homemade database from organs used for hydrolysate pro-duction. Moreover, these results suggest that Tilapia by-producthydrolysate contains a higher diversity of peptides than the pre-viously described shrimp hydrolysate. These first results provideinformation about the composition of one hydrolysate and allowstudying protein precursors which generate hydrolytic peptidesand their tissues localization.