[2][3] They are generally too small to be of interest to fisheries, although the relatively large Sicyases sanguineus regularly is caught as a food fish,[4] and some of the other species occasionally appear in the marine aquarium trade.
The greatest species richness is in tropical and warm temperate regions, but the range of a few extends into colder waters, like Diplecogaster bimaculata (north to Norway), Apletodon dentatus, Lepadogaster candolii and L. purpurea (all three north to Scotland; the last formerly mistaken for the mostly Mediterranean L. lepadogaster), Gobiesox maeandricus (north to Alaska), Gobiesox marmoratus and Sicyases sanguineus (both to southernmost South America), and Gastrocymba quadriradiata (from New Zealand's subantarctic islands).
As long as the strongly amphibious, intertidal-living species are kept moist by splashing waves, they can survive for up to three–four days on land, gaining oxygen from the air by the branchial surfaces (gills), skin and perhaps the mouth.
[2][17][18] Although several species can occur in brackish water, only seven (Gobiesox cephalus, G. fluviatilis, G. fulvus, G. juniperoserrai, G. juradoensis, G. mexicanus and G. potamius) from warmer parts of the Americas are freshwater fish that live in fast-flowing rivers and streams.
[19][20] Most known clingfish species are from relatively shallow coastal waters, but several inhabit the mesophotic zone and a few even deeper, with Alabes bathys, Gobiesox lanceolatus, Gymnoscyphus ascitus, Kopua kuiteri, K. nuimata and Protogobiesox asymmetricus reported from depths of 300–560 m (980–1,840 ft).
[21] Even in shallow coastal waters many clingfish are highly cryptic and easily overlooked, mostly staying under cover, although there are species that are active and will swim in the open.
[27] Three Gobiesox species that are restricted to fresh water in Mexico have not been rated by the IUCN, but are considered threatened by Mexican authorities.
Although the evidence presently is circumstantial, this strongly suggests that the world's smallest venomous fish is Acyrtus artius, which is less than 3 cm (1.2 in) long.
[32][33] Clingfish are named for their ability to firmly attach themselves to various surfaces, even in strong water currents or when battered by waves.
This ability is aided by their sucking disc, which is located on the underside at the chest and is formed primarily by modified pelvic fins and adjacent tissue.
[3] In a few clingfish species the disc is reduced or even absent, notably Alabes, which are quite eel-like in their shape and aptly named shore-eels.
[3][34][35] Species of deep water are often orange-red (these long wave-length colours are the first that disappear with depth, making them suitable for camouflage).
[22] Diademichthys lineatus, Discotrema species, Lepadichthys caritus and L. lineatus are strongly banded, which may function as a disruptive pattern when among sea urchin spines or crinoid arms, but may also be warning colours, as some members of these genera have poisonous skin and mucus (it is unknown if all of them are poisonous).
Most primarily feed on tiny crustaceans (such as amphipods, copepods, isopods, mysids, ostracods and shrimp) or gastropods (limpets and other sea snails).
[42] The 5th edition of Fishes of the World places the Gobiesociiformes in the clade Percomorpha as part of the series Ovalentaria.
A major authoritative work on the family is a monograph that was published in 1955 by J.C. Briggs,[44] but in the half century after its publication, up until 2006, fifty-six new clingfish species were described, or on average more than one per year.
[49] In 2020 the systematics of Gobiesocidae was reviewed and nine subfamilies were proposed: Cheilobranchinae, Chorisochisminae, Diademichthyinae, Diplocrepinae, Haplocylicinae, Gobiesocinae, Lepadogastrinae, Protogobiesocinae, and Trachelochisminae.