Lepomis gibbosus is one of the most widespread invasive freshwater fish species in Europe. Its ecological plasticity, broad trophic niche, and high adaptability facilitate its establishment in lentic ecosystems, where it may alter native communities and contribute to pathogen circulation. Besides its ecological impacts, this species may act as an epidemiological reservoir for infectious agents of relevance to wildlife and public health. Understanding its health status is therefore essential for assessing the ecological consequences of biological invasions. This study evaluated the sanitary status of pumpkinseed populations inhabiting ponds within the Crava Morozzo Nature Reserve and Madonna del Lago (Piedmont, NW Italy) during 2024-2025. At Madonna del Lago, fish sampling in 2024 preceded the complete drainage of the pond in 2025 as part of an invasive species eradication programme. Bacteriological analyses were performed on kidney, eye, and brain samples, while parasitological examinations were carried out on all collected specimens. Bacteriological investigations mainly revealed environmental bacterial communities together with opportunistic or potentially pathogenic taxa, including species belonging to the genera Carnobacterium and Pseudomonas. Parasitological analyses detected the zoonotic nematode Eustrongylides excisus in a limited number of specimens collected from Crava Morozzo in 2024. Although prevalence was low, the occurrence of this parasite confirms the involvement of L. gibbosus in the maintenance of pathogen life cycles within freshwater ecosystems. Our findings highlight the importance of integrating ecological epidemiology into invasive species monitoring programmes. Health surveillance of non-native fish provides valuable information on pathogen circulation, potential transmission to native fauna, and emerging zoonotic hazards. This integrated approach supports biodiversity conservation, invasive species management, and ecosystem health assessment within a One Health framework.