<p>This study investigates the functional guild composition and ecosystem health of the Mahanadi and Devi estuaries in Odisha, India, using the Estuarine Fish Community Index (EFCI), a multimetric tool integrating taxonomic richness, niche composition, nursery and breeding functions, and trophic guilds to assess estuarine condition. The study aimed to evaluate the impact of anthropogenic pressures on these ecosystems. The analysis revealed a total of 119 fish species across both estuaries, with the Mahanadi estuary exhibiting greater species diversity than the Devi estuary. However, the Devi estuary demonstrated a more favourable condition in terms of marine straggler and migrant species, indicating the increased saline water influx into the estuary. The freshwater stragglers and migrants were more represented in Mahanadi estuary showing its better connectivity with upstream species-rich stretches. The EFCI scores indicated that most sampling sites in both estuaries were classified as moderately impaired, with deviations from reference conditions ranging from 25 to 50%, except one site in the Devi estuary which was only slightly impaired (&lt; 25%). Metrics reflecting taxonomic richness and niche composition were higher in the Mahanadi estuary, while trophic guild metrics, particularly those related to detritivores, were better in the Devi estuary. The lower detritivore scores in the Mahanadi estuary can be attributed to the negative impacts of sand mining, which disrupts detritus-based food webs. The study signifies the considerable influence of anthropogenic activities, including sand mining, mangrove destruction, aquaculture, and industrial pollution, on estuarine health. The EFCI proves to be a valuable tool for translating complex ecological data into actionable insights for management and policymaking. This research highlights the need for targeted conservation efforts to address the specific pressures affecting estuarine ecosystems, ensuring their continued functionality and biodiversity.</p>