Ontogenetic changes in morphology and habitat use were studied for three species of the genus Diplodus (Pisces: Sparidae) from the Mediterranean Sea. From the settlement of larvae into the benthic environment to the recruitment of juveniles into adult habitats, two ecomorphological stages were determined. The first stage (transition juvenile) corresponds to fish from about 6.6 mm (settlement) to 22.5 mm SL (21.0–23.5 mm depending on species). During this period, fish acquire early morphological adaptations to the benthic habitat, become pigmented, and are restricted to specific settlement habitats in the nursery zone. The second stage (post-transition juvenile) corresponds to fish from about 22.5 mm to an average 43.7 mm SL (39.5–48.5 mm depending on species). During this period, fish complete their morphological adaptation to benthic life and colonize the whole nursery zone. Fish longer than about 43.7 mm become immature adults as they possess all the characteristics of adults except sexual maturity, and start leaving the nursery zone to colonize adult habitats. This phase corresponds to the recruitment of juvenile fishes. Finally, we developed a complete life-history model for Diplodus, analysed the extent to which our model can be extended to other demersal species and recommend the limits in size of each life stage be precisely defined for every study of post-settlement processes.