Brooklynella hostilis is a brackish and marine parasitic disease, it is a protozoan ciliate that parasitizes the skin and gills. The back of the head to the dorsal fin seems to be the main target, and this makes it easier to notice and identify. If in the gills much more difficult to notice, yet a tell-tale sign is hanging just under the surface, gasping for air. Is a ciliate holotrichous, completely ciliated, is of the family Dysteridae. Very aggressive and rapid just as Chilodonella cyprini in freshwater.