The transcriptomes of the seabream larvae farmed in different European commercial hatcheries were analyzed during critical larval stages to evaluate fish larvae's biological capacity and optimize larvae production under hatchery conditions. Samples were collected from the gilthead seabream (Sparus aurata) hatcheries in Greece (site Gr), Italy (site It), and France (site Fr). The RNAs were extracted from larvae with different weights, mainly at the flexion (23 and 25 days) and mid-metamorphosis stages (43, 50, 52, 56, and 60 days). RNA-seq libraries were sequenced using the Illumina HiSeq xten. The differential expression and function of genes obtained from comparing transcriptomic profiles of larvae at different developmental stages can help to improve marine-farmed fish larvae production during critical larval stages and identify age/quality-related gene markers.