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 are relatively small, typically less than 10 cm in length. Gobies include some of the smallest vertebrates in the world, like species of the genera Trimmatom nanus and Pandaka pygmaea, which are under 1 cm long when fully grown. The most distinctive aspects of goby morphology are the fused pelvic fins that form a disc-shaped sucker. Gobies can often be seen using the sucker to adhere to rocks and corals. Gobies are primarily fish of shallow marine habitats including tide pools, coral reefs, and seagrass meadows. Adapted from Wikipedia.