The smell of decaying flesh is highly repellent to many species, but the chemical basis for that aversion has been elusive. Using zebrafish as a model organism, Sigrun I. Korsching of the University of Cologne, in Germany, and coworkers have for the first time identified an olfactory receptor, TAAR13c, that responds to cadaverine, a diamine that is the main odorant in rotting flesh (Proc. Natl. Acad. Sci. USA 2013, DOI: 10.1073/pnas.1318596110). TAAR13c showed no response to related molecules lacking an amine at each end, suggesting the presence of two remote recognition sites on the receptor that must both be occupied to trigger a response. The receptor did respond to other C4 to C8 diamines, including putrescine, another product of protein decay. The identification of an olfactory sensor for such odors could provide researchers a chemical handle to study the biochemistry and neurology of aversion or attraction behaviors in animals related to zebrafish.