<p>Understanding fish assemblages in lentic ecosystems and the factors influencing them is crucial for effective management and conservation. Yet, data on lentic ecosystems in the Eastern Mediterranean are scarce. To bridge this gap, we conducted a comprehensive study, gathering fish data from 16 lentic Greek water bodies, including natural lakes, reservoirs, and heavily modified water bodies. Sampling was performed once per water body between 2010 and 2023, following a standardized gillnet protocol. Our study aimed to address two key questions: (1) which genera dominate fish assemblages and (2) which environmental and anthropogenic drivers shape dominance patterns. Generally, the Leuciscidae family accounted for more than 50% of the total abundance and biomass catches, with few exceptions. At the species level, a single species often dominated catches, contributing over 50% of total abundance or biomass. Non-native species, including introduced and translocated ones, were prevalent in 6 out of 16 water bodies, especially the most modified ones. Cluster analysis revealed similarities among water bodies within the same ecoregion/ichthyoregion due to high fish fauna endemism. Canonical correspondence analysis (CCA) indicated that altitude, drainage area, total phosphorus concentrations and Lake Habitat Modification Score (LHMS) were the main environmental variables explaining variation in fish family catches. Our findings underscore the influence of regional, environmental and anthropogenic factors on Greek lentic water body fish assemblages, including species introductions and hydromorphological alterations. This study contributes essential baseline data for regional conservation planning in Mediterranean inland waters.</p>