The gobies form the family Gobiidae, which is one of the largest families of fish, with more than 2,000 species in more than 200 genera. Most of them are comparatively small, less than 10 cm (4 in) in length and include some of the smallest vertebrates in the world, such as species of the genera Trimmatom nanus and Pandaka pygmaea, which are under 1 cm (3/8 in) long when fully grown. Some large gobies, like some species of the genera Gobioides or Periophthalmodon, can reach over 30 cm (1 ft) in length, which is exceptional.
Apart from food for humans and other larger fish such as cod, haddock, sea bass, and flatfish, several gobies make good aquariums mate, such as the bumblebee gobies of the genus Brachygobius.
The most distinctive feature of goby is the fused pelvic fins that form a disc-shaped sucker. Gobies 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.
Gobies are primarily found in shallow marine habitats, including tide pools, coral reefs, and seagrass meadows. They are also found in brackish water and estuarine habitats, including the lower reaches of rivers, mangrove swamps, and salt marshes. A few are also found in freshwaters. Most gobies feed on small invertebrates, although some of the larger species eat other fish, and a few, also eat planktic algae.
Several species of gobies are kept in aquaria. Most of them are from saltwater, and make excellent additions to healthy reef or fish-only aquariums. The most popular is the small but colorful neon goby (Elacatinus oceanops).
Most gobies stay toward the lower portion of the aquarium, hiding in the rock but some species (most notably the shrimp gobies) prefer to dig themselves little burrows. Potential keepers of these striking fish should provide them with a fine-grained substrate to prevent damage to the undersides of their tank.
Commonly kept saltwater species include the Randall’s shrimp goby, Black barred convict goby, Black clown goby, Bluespotted watchman goby, Catalina goby, Cave transparent goby, Citron clown goby, Court jester goby, Diagonal bar prawn goby, Diamond watchman goby, Dracula gobi, Engineer goby, Gold neon eviota goby, Green-banded gobi, Green clown goby, Hector’s gobi, Hi fin red banded goby, Orange marked goby, Orange spotted goby, Orange stripe prawn goby, Pink spotted shrimp goby, Pink bar gobi, Red head goby, Sleeper banded goby, Sleeper blue dot goby, Sleeper gold head goby, Sleeper railway glider goby, Sleeper striped goby, Steinitz goby, Tangaroa goby, Tiger watchman goby, Two spot goby, Wheeler’s watchman goby, Yellow watchman goby, Yasha gobi, Yellow clown goby, Yellow priolepis goby and Yellow stripe clingfish. These are mostly colourful and the care level for all of these is easy to moderate. The bumblebee gobies from the genus Brachygobius are perhaps the most widely traded freshwater species, being small, colorful, and easy to care for. They need tropical, hard and alkaline freshwater or slightly brackish conditions to do well.
Gobies are generally peaceful towards their tankmates, though territorial among themselves. Since most are small and few are predatory toward other fishes, they make good community fishes. The main problem with gobies is feeding them. With a few exceptions, the small species prefer live or frozen foods rather than flake and they are not even good at competing with other active species such as cichlids. Another problem is that they commonly jump out of the tank, so having a tight-fitting lid is a must. They are recommended to be kept on their own or with peaceful surface dwelling species, such as halfbeaks and guppies.
They are hardy and do not harm invertebrates which makes them a good choice of fish for a reef tank.