The aim of this study was to complete and fully characterize the proteome of rainbow trout coelomic fluid (CF). Furthermore, we intended to identify the proteins responsible for the extension of egg viability in salmonids coelomic fluid. For this, the proteomic composition of different salmonids CF and non-salmonids CF were compared to identify proteins specifically present in salmonids CF. Those proteins could be responsible for the egg conservation property of the salmonids CF. In parallel, rainbow trout CF has been fractionated using HPLC coupled to gel filtration or ion exchange columns. We have then tested the egg conservation properties of the different fractions obtained. Proteins present in the fractions allowing egg quality preservation were identified. Identifying the CF components involved in egg viability would have important applied outputs with various biotechnological applications for aquaculture. It could help understanding egg quality preservation mechanisms, and consequently improving egg storage condition.