[1] Most of gobiid fish are relatively small, typically less than 10 cm (3.9 in) in length, and the family includes some of the smallest vertebrates in the world, such as Trimmatom nanus and Pandaka pygmaea, Trimmatom nanus are under 1 cm (3⁄8 in) long when fully grown, then Pandaka pygmaea standard length are 9 mm (0.35 in), maximum known standard length are 11 mm (0.43 in).

[2][3] The most distinctive aspects of gobiid morphology are the fused pelvic fins that form a disc-shaped sucker.

The species in this family can often be seen using the sucker to adhere to rocks and corals, and in aquariums they will stick to glass walls of the tank, as well.

Gobiidae are spread all over the world in tropical and temperate near shore-marine, brackish, and freshwater environments.

Before the revision the Gobiidae contained six subfamilies: Gobiinae, Benthophilinae, Amblyopinae, Gobionellinae, Oxudercinae, and Sicydiinae.

In addition, species formerly placed in the families Kraemeriidae, Microdesmidae, Ptereleotridae and Schindleriidae were added to the revised Gobiidae, although no subfamilies were described.

[7] The two formerly recognised subfamilies where the species have been retained in Gobiidae in the 5th Edition of Fishes of the World:[7] Members of Benthophilinae are endemic to the Ponto-Caspian region (including the Marmara, Black, Azov, Caspian, and Aral Seas).

Gobiids are primarily fish of shallow marine habitats, including tide pools, coral reefs, and seagrass meadows; they are also very numerous in brackish water and estuarine habitats, including the lower reaches of rivers, mangrove swamps, and salt marshes.

A few gobiid species (unknown exactly, but in the low hundreds) are also fully adapted to freshwater environments.

Most species in the Gobiidae attach their eggs to a substrate, such as vegetation, coral, or a rock surface.

The larvae are born transparent, and they develop coloration after spreading to find a suitable habitat.

The larvae of many freshwater gobiid species are carried downstream to the brackish waters, or even to the sea.

The total lifespan of gobiid varies from one to ten years, again with the species in warmer waters generally living longer.

[11] Many species in the Gobiidae live in male-female pairs that construct and share burrows, similar to many other fish such as Mozambique tilapia.

Gobiids use their mouths to dig into the sea bottom, removing dead coral-fragments, rubble, and benthic algae in order to build their burrows.

Females primarily maintain the burrow, and males mainly care for the eggs by fanning them, thereby providing oxygen.

Since not all males have large bodies, the smaller ones may cheat instead of expending energy to find mates.

Sex change is possible in these gobies, since the external genitalia for males and females do not differ much.

Gobiodon histrio from the Great Barrier Reef exhibits bidirectional sex changes.

[18] Sex determination in coral goby Gobiodon erythrospilus does not occur until the juveniles meet potential mates.

The shrimp has poor eyesight compared to the gobiid, but if it sees or feels the fish suddenly swim into the burrow, it will follow.

Each party gains from this relationship: the shrimp gets a warning of approaching danger, and the fish gets a safe home and a place to lay its eggs.

These gobiids, known as "cleaner gobies", remove parasites from the skin, fins, mouth, and gills of a wide variety of large fish.

Again, this is a relationship where both parties gain: the gobies get a continual supply of food as bigger fish visit their cleaning stations, and the bigger fish leave the cleaning stations healthier than they were when they arrived.

Another form of symbiosis exists between gobiids and the mushroom coral Heliofungia actiniformis (Fungiidae), in which representatives of the genus Eviota roam among the tentacles possibly hiding from predators.

Aquarists typically provide them with a fine-grained substrate to prevent damage to their delicate undersides.