Caligus rogercresseyi is an ectoparasitic copepod that negatively affects the salmon farming industry, causing economic losses. To use phytochemicals as feed additives, or other chemicals that could elicit behavioral responses in C. rogercresseyi, the chemosensory recognition process is crucial. Therefore, to establish how C. rogercresseyi recognizes glucosinolates and their derivates isothiocyanates, a chemosensory protein (CSP) described as specific carrier of these chemicals in sea louse (CrogCSP) was identified in this study. The recombinant CSP and its selectivity against different chemical compounds was tested by fluorescence binding assays. Phylogenetic analysis revealed a close relationship among CrogCSP and other reported CSPs. Our results indicate that phenyl isothiocyanate and isophorone exhibited dissociation constants of 4.17 and 4.28 μM of K