At times regarded as an Order of advanced bony fishes (Gobiesociformes) or a suborder of the Perciforms (Gobiesocoidei), the Clingfishes are a sizable group (36 genera, about 120 species) of small (most under 7 cm.) freshwater, brackish and marine fishes rarely seen in the ornamental aquatics trade. This could change (likely so) with an increasing emphasis on "reef" systems displaying more esoteric commensal relations between species of invertebrates and fishes... as many Clingfishes are found in such associations (mainly with crinoids and urchins).

     Mostly marine bottom-dwellers (lack swim-bladders), almost all with pelvic fins modified into a sucking disk (hence their common name).