They are usually mid-sized to small
ray-finned fishes; some are very colorful, while others are
cryptic. Most true gobies are less than long when fully grown. The largest species
Glossogobius giuris can reach up to ; the smallest known species as of 2010,
Trimmatom nanus, is just about in length when fully grown, making it one of the smallest
vertebrates. In many true gobies, the
pelvic fins have grown together into a suction cup they can use to hold on to substrate. Most have two
dorsal fins, the first made up from spiny
fin rays, while the other has some spines in the front followed by numerous soft rays. They are most plentiful in the
tropical and
subtropical regions, but as a group are almost
cosmopolitan in
marine ecosystems. A few
species tolerate
brackish water, and some –
Padogobius and
Pomatoschistus species – even inhabit
fresh water. They are generally
benthic as adults (the
spawn can distribute widely by
ocean currents), only
Sufflogobius bibarbatus is noted to be quite
pelagic throughout its life. Most inhabit some sort of burrow or crevice and are somewhat
territorial. In some cases, they live in
symbioses with unrelated animals, such as
crustaceans. The larger species are fished for food, in some cases on a commercial scale. Many Gobiinae species are popular
aquarium fish. Especially popular are the colorful species, some of which are regularly traded. In general, the interesting behavior and bold habits make most true gobies seem attractive pets. However, their territoriality and because even the smallest species are fundamentally
carnivorous and need living food to thrive make them not easy to keep (particularly compared to the related family
Eleotridae). As typical for
oceanic fishes, many Gobiinae tend to be almost impossible to breed in captivity, and some species have become rare from
habitat destruction and
overfishing. ==Genera==