[6][10] Myzobdella lugubris lives in brackish and fresh water and cannot tolerate high salinity waters- in this case, above 26 PSU- for very long.

[4][11][1][14][15] Besides laying its eggs on and being commensal with crustaceans, Myzobdella lugubris is a semi-permanent parasite on over forty fish species, and, in one instance, a turtle, displaying little host preference.

[18] The severe lesions it causes on the undersides of the heads of catfish often become infected with fungus, of the genus Saprolegnia and other related filamentous fungi.

[16] Several bacteria have been reported from the leech's viscera, the most notable being Flavobacterium psychrophilum, a bacteroid responsible for Bacterial cold water disease.

[9] Myzobdella lugubris is an invasive species in many parts outside its native range, having been introduced to Western North American Waters, Hawaii, and even in the Adriatic Sea.