In order to improve Our understanding of factors determining egg quality in fish, seabass egg batches obtained from 34 females held under standard conditions, were assessed for biological performances and a fraction from each batch was subjected to proteomic analysis. Comparison of proteomic patterns from eggs of different quality revealed differential protein spots among which one was identified as Nucleoside Diphosphate Kinase, a highly conserved protein involved in cell proliferation. This study shows that molecular markers may help understand factors determining egg quality in fish.