During a photo-identification survey for a study of area use and social organization of marine tucuxi dolphins (Sotalia guianensis) in an estuarine area in south-eastern Brazil, a remora or discfish was recorded attached to one dolphin in a group of 25. The record place (water salinity 28 psu at the record time) is about 23 km from the closest connection between the estuary and the open sea. The discfish was identified as a sharksucker (Echeneis naucrates). This is the first record of a remora on a marine tucuxi dolphin. Besides adding a new host to the cetacean species which are known to carry remoras, our record strengthens the recent suggestion that sharksuckers use coastal dolphins as hosts.

The sharksucker, Echeneis naucrates, attaches to a variety of hosts including teleost fish, elasmobranchs, marine turtles, and mammals. We list 18 additional hosts not previously recorded for this species, including the first report of its attachment to a conspecific and review the possible role of the relationship between echeneid fish and their hosts. The attachment of E. naucrates to a conspecific represents an addition to known hosts for this species, but it remains unclear if remoras are a habitual host for conspecifics.