Understanding the behavioral response of estuarine fishes to environmental contaminants is critical for assessing the ecological consequences of disturbances. Here, we examined geographic variation in avoidance behavior to petroleum-contaminated sediments in the Gulf killifish (Fundulus grandis), a sentinel species in northern Gulf of Mexico marshes. Adult fish were collected from four geographically distinct estuaries: Terrebonne Bay, Louisiana; Mississippi Sound, Alabama; Pensacola Bay, Florida; and Cedar Key, Florida. Choice experiments tested fish preference to either uncontaminated sediments or sediments contaminated with fresh or weathered oil. Results found significant differences among source locations with individuals from western Gulf sites (Louisiana and Alabama) exhibiting strong avoidance of fresh oil, while those from eastern sites (Florida) showed limited or no avoidance. No source location avoided weathered oil. These findings suggest that sensitivity to oil contamination varies regionally, potentially reflecting local exposure histories, environmental adaptation, or other sources of geographic variation. The diminished response to weathered oil across all locations highlights a reduced ability to detect residual contamination and indicates that these fish may use more volatile compounds that precipitate or degrade faster as a cue. This study underscores the importance of incorporating behavioral and geographic-level variability into impact assessments and emphasizes the need for regionally-tailored conservation strategies.