This study was conducted on the Marchica lagoon, a designated Ramsar site regionally recognized for its biological, ecological and socio-economical value. Intensive Ichthyofaunal inventories carried out during the post-stabilization of the inlet (after 2011), mainly between 2015 and 2016, documented 86 teleostean fish including 55 earlier reported species and 31 newly recorded ones. Consequently, the updated checklist of the Marchica lagoon's ichthyofauna (1908-2016), increased to 112 species, belonging to 33 families. Sparidae (17 species) is the richest family. Out of the updated checklist, 89 (79.46%) and 19 (16.96%) were categorized as marine and resident species respectively indicating that the Marchica lagoon is largely typified by nursery-dependent species. More than half of the fish fauna recorded in the lagoon is strictly or partially benthivores. The checklist also documents 10 threatened species under different categories of conservation status. According to the functional approach, ichthyological evolution before (1908-2011) and after hydraulogical intervention (2011-2016) is marked in terms of the ecological guild by an increase in the number of marine species. This fact is supported by management actions implemented after 2011, particularly the opening of the new large pass, allowing a large variety of marine species to enter the lagoon. Regarding the trophic guilds, the most remarkable changes before and after 2011, concerned the strictly or partially benthivorous species. This is supposed a significant evolution within the Marchica lagoon benthic habitats, following the opening of the artificial inlet since 2011. Recent concerns about global environmental changes suggested that a similar study of long-term population changes is required including not only the presence of species or families but also the total diversity, biomass, and population dynamics, as growth, reproduction, mortality and productivity.