<p>Given the complex and dynamic characteristics of floodplain systems, it is important for researchers to consider both the taxonomic composition and the trophic guild structure of ichthyofauna. Taxonomy-based analyses are robust in revealing regional and local patterns of species distribution and abundance, while trophic analysis allows for a more comprehensive understanding of the ecological relationships among species and their connections with the environment, especially in highly diverse communities. Thus, we sought to assess the influence of environmental variables on the taxonomic and trophic composition of fish assemblages at lake beaches associated with the Amazon River in the Central Amazon during the dry season. The results of the canonical correspondence analysis showed strong correlations between species distribution and key environmental variables, particularly dissolved oxygen, temperature, pH, and conductivity, suggesting that taxonomic composition is predominantly influenced by limnological conditions that may reflect species’ physiological limitations in occupying certain environments. Analyses based on trophic guilds did not show statistically significant relationships with environmental variables but revealed qualitative patterns along environmental gradients, indicating weak tendencies in the functional organization of assemblages. Taken together, these results suggest that functional approaches can serve as complementary tools to taxonomic analyses for exploring subtle ecological responses to environmental variation in floodplain systems. This highlights the value of integrating taxonomic and functional perspectives when assessing ecosystem-level processes in highly dynamic habitats such as Amazonian lake beaches.</p>