In fish, the chemosensory system is highly developed and very important for a wide range of activities like navigation, mate recognition, and food searching. The taste receptors family show a dynamic evolution in land-living vertebrates, with as little as 2–3 functional genes in some avian species and more than 50 genes in an amphibian species. In contrast, teleost fish appeared to have a small and rather constant repertoire of 3–6 bitter taste receptor (T2Rs) genes. We are investigating the molecular and bio chemical characteristics of T2Rs gene in this animal. We try to see the importance of the chemosensory system in fishes and then try to understand the crosstalk between the different sensory systems in vertebrates.