” My research examines how the thermal niche of early life stages can predict the establishment success of invasive fish species. While most studies focus on adult thermal constraints, earlier stages, and particularly larvae, are known to be sensitive to temperatures. By analysing species-specific abundance data of larvae and adults from both the source (Red Sea) and invaded (Eastern Mediterranean) regions, I compare the thermal niches of these life stages. This approach offers new insights into the role of thermal tolerance in invasion success. As biological invasions and rising temperatures intensify, understanding thermal limits across ontogeny is crucial for assessing invasion potential and pathways.”