Parasitism in some east Atlantic bathypelagic fishes with a description of Lecithophyllum irelandeum sp. n. (Trematoda).

Eighty-four bathypelagic fishes collected at depths from 975 to 1,555 m in the eastern Atlantic Ocean were examined for animal parasites. Ninety-five percent (including all the Gonostomatidae) were free from parasites. A digenetic trematode, Lecithophyllum irelandeum sp. n. from the stomach of one specimen of the family. Melamphaidae, is described. One copepod was found in the kidney of Bathylagus euryops, and another copepod infected the liver of a melamphaid. This paucity of parasites is of a different pattern from that found in mesopelagic waters. Some environmental factors that may be involved in the causes of this differences are mentioned.