The evolution of organismal cue-response systems can allow for an effective behavioral reaction to various environmental signals. In aquatic habitats, the reception of certain chemical cues can increase individual fitness of organisms by serving as an indicator of predation threat. In some fish species, damage to an individual's epidermal cells causes release of a substance that functions as an alarm cue and consequently initiates defense responses in neighboring prey. Recent research on the chemical makeup of the substance that elicits an anti-predator response in Danio rerio (Hamilton) (Zebrafish) revealed that chondroitin fragments were a key component in this substance. The goal of our study was to investigate the ability of chondroitin to elicit an alarm response in Fundulus catenatus (Storer) (Northern Studfish). This species is a small-bodied killifish native to southeastern to south-central USA and is associated with topwater habitats near aquatic and/or overhanging vegetation. We hypothesized that reduced movement and/or a change in position in the water column would be a likely response of the Northern Studfish to chondroitin. We experimentally observed Northern Studfish behavior before and after the addition of chondroitin and a control substance, and compared the fishes' behavioral responses. Our results show that the Northern Studfish that were exposed to chondroitin tended to reduce their movement by sevenfold and were more likely to move to the bottom of the aquarium relative to the control group, suggesting that chondroitin potentially serves as an alarm-cue component in this species. Our study represents the first demonstration of Northern Studfish response to a chemical cue and the first time that chondroitin sulfate has been shown to elicit a component of alarm behavior in a stream fish. We discuss our findings in relation to potential uses of chondroitin as an alarm cue in the conservation of imperiled stream fishes.