Environmental conditions in estuarine habitats can vary greatly and influence the composition of fish assemblages and their trophic interrelationships. We investigated feeding habits and patterns of diet overlap in juvenile plaice (Pleuronectes platessa) and flounder (Platichthys flesus) from two estuarine habitats in the Irish Sea. Plaice was found to vary its diet significantly across environments, whereas flounder exhibited a more consistent and homogeneous feeding pattern. Importantly, sympatric fish sampled at the same station were shown to reduce diet overlap. The results support the view that environmental heterogeneity in estuaries maintains a wide range of selective forces, the net outcome of which can produce a diverse array of feeding adaptations among interacting species.