[1] The genus currently includes 16 species, which are all parasitic on the gills of marine fish of the family Lethrinidae and Nemipteridae.

The digestive system includes an anterior muscular pharynx, and two lateral intestinal branches (or caeca); as in all Platyhelminthes, there is no anus.

The characteristics of the lamellodisc, without paired elements, is the main character which differentiate Calydiscoides from other genera of the family Diplectanidae.

Relationships of Calydiscoides Young, 1969 with Protolamellodiscus Oliver, 1969 are not clear; the two genera were described almost simultaneously, and it might be that they are synonym.

[2][4] Hosts of species of Calydiscoides are only members of the families Nemipteridae (threadfin breams) and Lethrinidae (emperors).