Diplectanids are small animals, generally around 1 mm in length.

As parasites, they can be extremely numerous, up to several thousand on an individual fish.

The family Diplectanidae was proposed by the Italian parasitologist Monticelli in 1903 (as subfamily Diplectaninae).

[1] The status of the family and its components was later examined by various authors, including Johnston & Tiegs (1922),[2] Price (1937),[3] Bychowsky (1957),[4] Yamaguti (1963),[5] and Oliver (1987).

[6] Diplectanids are diagnosed by the combination of these three characters: The genera recognized in WoRMS [7] are: