Fishes of the World classified these families and the Anabantiformes alongside Synbranchiformes, Carangiformes, Istiophoriformes and Pleuronectiformes in a monophyletic clade which is a sister taxon to the Ovalentaria but to which the authors do not assign a rank or a name.

[2] According to FishBase, the family includes three genera: Nandus of South and Southeast Asia with several species, and the monotypic Afronandus and Polycentropsis of tropical West and Middle Africa.

[1] Most recent authorities place the two African genera in the South American leaffish family, Polycentridae, which is only distantly related to Nandus (the "true" Nandidae).

[4] These fish usually have a coloration that appears to have evolved to resemble dead leaves, and very large protractile mouths.

Those features, along with their peculiar movements (seemingly intended to resemble a leaf innocently moving through the water) help them to catch fairly large prey compared to their body size, including small fish, aquatic insects, and other invertebrates.