Catoessa boscii (Bleeker, 1857) (Crustacea, Isopoda, Cymothoidae), is redescribed according to the type specimen observed by Schioedte and Meinert (1884) extant in the Rijksmuseum von Natuurlijke Historie, Leiden (RMNH) and from many additional specimens recently collected in India from Carangoides malabaricus (Pisces, Carangidae). This study allows an updating of the diagnosis of the genus Catoessa and of the species Catoessa boscii. Some parasite-host relationships were studied during the year. Prevalence and sex ratio of parasites varied according to the month, and the sex and size of hosts.