Human-mediated species introductions have provoked innumerable biological invasions, which are contributing to the biotic homogenization of global flora and fauna. Despite extensive research, we lack simple methods of predicting how and where an introduced species will spread and establish. We predict that spread can be modelled simply using the characteristics of the invading population, while establishment should be explained by the characteristics of the receiving ecosystem. Using the brown trout (Salmo trutta) invasion on the Island of Newfoundland as a case study, we fit a reaction-diffusion model to brown trout population data to predict expected spread and test these predictions against extensive occurrence data. Next, we use statistical models to assess the influence of several environmental variables on brown trout establishment patterns. We find that observed spread in Newfoundland is slow and that it lies on the lower end of the range of predictions made by the reaction-diffusion model. Two landscape-level environmental variables explain establishment patterns, but their influence is likely moderated by other factors. The wide range of predictions made by the model point to the importance of using population-specific parameterization and the intricate interplay of environmental variables that influence establishment illustrates the need to consider both landscape factors that are generally applicable across biological invasions, and those that are more specific to the ecology of the invader. Our study contextualises the mechanisms that contribute to a slow aquatic invasion and reveals that studies need to integrate a variety of methods to elucidate the processes governing invasions.