Competition between invasive and native species can result in exploitation of resources by the invader, reducing foraging rates of natives. However, it is increasingly recognised that multiple factors can enhance the resilience of native species competing for limiting resources with invaders. Although extensively studied in terrestrial species, little research has focused on behavioural plasticity in the aquatic realm and how this influences native species resilience. Here we examined the role of behavioural plasticity in interactions between a native Australian fish, Pseudomugil signifer, and a widespread invasive fish, Gambusia holbrooki. To determine whether P. signifer displays behavioural plasticity that may mitigate competition with G. holbrooki, we first quantified social behaviours (aggression, submission and affiliation) and shoal cohesion for each species in single and mixed species groups. Secondly, we compared the feeding rates of both species in these groups to ascertain if any modulation of social behaviours and cohesion related to foraging success. We found that some behaviours, namely aggressive and submissive behaviours of G. holbrooki and P. signifer, respectively, showed plasticity in the presence of heterospecifics but that other behaviours, namely social affiliation, shoaling and foraging, remained inflexible. This variation in the degree of plasticity highlights the complexity of the behavioural response of a native species and suggests that both behavioural modulation and consistency promotes native species resilience in the form of sustained foraging efficiency in the presence of an invader.