Urban fish communities are established in a myriad of ways, not least of which is that associated with water delivery to populated areas. In Arizona, much of our water is delivered by canals. It is well known that these canals house many species of fish, form the source waters, and from bizarre introductions by the general population. Given that many, if not most, of the bodies of water within Arizona are highly altered in some way by human activities, understanding the fish communities that persist within these artificial waterways is fundamental to a larger understanding of the region's aquatic ecosystems. As a first look at the canal community, we are using stable isotope analysis for detecting long-term diet signatures. We seek to determine if the diet is canal-based, meaning the fishes have potentially established residency in the system. We hypothesize that many of the species are resident in the canals, and even reproducing there. These fishes have their own community that is maintained over long periods of time, ranging from months to even years (depending on the persistence of water). Therefore, we hope to gain an understanding of how these fishes interact with one another and the unique physical environment created by the canals. These fishes will continue to be sampled in order to investigate a number of different aspects of this urban community including genetics (to determine relatedness of canal fishes to stocks in natural and semi-natural waterways), metrics of pollution load (as they affect animal reproduction, growth, behavior and morphology), and eventually laboratory studies of live fishes to quantify behavior and functional morphology (to determine exactly how these fishes interact).