The impacts of urbanisation on aquatic ecosystems have been well described and include; a loss of riparian vegetation, flashier hydrology, altered channel morphology, elevated concentrations of toxicants and associated poorer water quality. These impacts in turn have consequences for algal biomass and organic matter inputs. The ultimate effects on the aquatic invertebrate biota include a decrease in sensitive taxa, an increase in tolerant taxa and an overall decrease in invertebrate richness and abundance. Many of these factors have been related to platypus presence, suggesting that increasing urbanisation will affect the platypus, its diet; habitat and distribution. Trophic relationships of the platypus were investigated at three sites spanning a gradient of urbanisation in Victoria during autumn, 2013. Food webs were compared using stable isotope analysis of platypus fur, basal carbon resources and potential dietary items. The consumption of a wide range of invertebrates at all sites indicate the flexibility of the platypuses’ diet and suggest that it is likely to be factors other than food supply that have resulted in local declines in the presence of platypus.