Gobioidei

Gobiidae

The family Gobiidae, made up of fish called gobies, are the largest marine family of fish with around 1,950 different species. Gobies commonly have their pelvic fins fused together, which allows them to use their pelvic fins as a suction device to keep them anchored on a hard surface such as a rock or piece of coral. Gobies often live in association with invertebrates such as sponges and sea urchins in or around corals both soft and hard; however, some species live on bare mud and sand. Gobies are typically small fish; many do not exceed a total length of 10 cm. Some of the smallest fish in the world belong to this suborder such as the Trimmatom nanus. This species, found in the Indian Ocean, is only 8–10 mm as an adult. The largest of the gobiids is found in the South Atlantic and Caribbean region; the violet goby, Gobioides broussenetti, can grow to a length of 50 cm; this goby. which is purple in color. resembles an eel with its elongated anal and dorasl fins. Some gobies in the genera Periophthalmus and Boleophthalmus are practically amphibious, meaning they can breath in and out of water. Species such as the Atlantic mudskipper (Periophthalmus barbarus), which can grow to a length of 25 cm, can actually breath air. These gobies skip across the mud of intertidal flats in mangrove swamps in search of food; adults feed mostly on crabs, insects, and other arthropods.

While most of the species in this family are found in a marine setting, some species inhabit freshwater streams and lakes, some of which are important to island stream assemblages. Species such as the red-tailed stream goby (Lentipes concolor) are able to use their fused pelvic fins as a suction device which enables them to ascend rock faces alongside waterfalls, allowing them to inhabit waters far from the ocean.

Kraemeriidae

The members of the family Kraemeriidae are known as the sand gobies because these particular gobies regularly rest in the sand with just their heads showing. The genus Knipowitschia is one of the five genera in the kraemeriid family. Fifteen different species are found within the genus Knipowitschia; the Vrgorac goby (Knipowitschia croatica) is one of them. This species is found in the Black Sea and surrounding seas such as the Caspian and Adriatic. It can grow up 5 cm, but reaches sexual maturity at an early age, being able to reproduce at a length of 45 mm. Females lay a clutch of 200 to 600 eggs. Spawning occurs from March to November, but the majority of spawning activity occurs between April and September.

Rhyacichthyidae

The specimens within the family Rhyacichthyidae are known as the loach gobies; these fish are found in and around Indonesia and Australia. The third of their body towards their tail is fairly flat; this adaptation, along with their pelvic fins serving as a suction cup, allows them to withstand very strong currents.

Eleotridae

The family of Eleotridae are often referred to as sleepers because these fish usually lie still on the bottom as if they were asleep. They have a wide range and are distributed in tropical and subtropical regions in estuaries and streams. The Eleotridae are often primary predators in streams and ocean islands in and around areas such as Hawaii and New Zealand, where larger predators are absent. Although these species are native to the Indonesian area of the Pacific, they are expanding their range to the southwestern Atlantic along the coast of Brazil. The species Butis koilomatodon has been found on the eastern coast of Brazil, in 1989, but was not identified until 2000. As of the summer of 2012, 23 specimens of B. koilomatodon have been collected along the coast of Brazil, all specimens were collected at six different locations along the coast. Biologists have been able to identify 17 of the specimens as male, four as female, and two more were not able to be sexed. And many of the specimens were in different stages of maturity, a breeding population is likely to be established, but enough data are collected to conclude it finally. How this species got to the other side of the continent of South America is unclear. Many believe they were brought over in the ballast tanks of ships. The small size (10 cm maximum) of the species makes it very easy for them to enter the intake holes on a ship's ballast tank. Also, their able to tolerate a wide range of salinity levels, as well as temperature fluctuations, makes it likely for them to inhabit a ballast tank on journeys across the ocean.

Microdesmidae

This group is often referred to as the wormfish family. These are similar to the fish from the Kraemeriidae in the fact that they, too, submerge themselves in the sand and mud. The only difference is the anatomical appearance of the Microdesmidae family; these small fish often resemble an eel.

Ptereleotridae

The fish within the family Ptereleotridae have several names associated with them: dart fish, fire fish, and hover gobies because of their bright coloration, as well as their ability to hover just above the bottom of the reef, whereas most gobies are actually lying on the bottom most of the time. Some are called dart fish because when threatened or frightened, they quickly dart to a burrow beneath a rock or other structure. The Chinese zebra goby (Ptereleotris zebra) is an example of a fish from this family; Ptereleotris zebra can reach a maximum length of 12 cm and is usually found in and around reefs at depths from 2–31 m, but predominantly at 2–4 m. The native range of the Chinese zebra goby is in the Indonesian Pacific area, occupying the Great Barrier Reef, as well as the Red Sea and the Marshall Islands of Micronesia. This schooling species stays in groups and many can be found in the same refuge at once.

Schindleriidae

This family contains only three species, the fewest number of all the families in the suborder. These species are collectively referred to as "infant fishes" due to their characteristic neoteny (retention of juvenile traits into adulthood). These fish reach sexual maturity at a length of 2 cm, retaining other larval traits including lack of pigmentation, a larval kidney, and an unossified skeleton.

Species status

The tidewater goby (Eucyclogobius newberryi) was listed as an endangered species in 1994; it is the only species of goby in the genus Eucyclogobius. E. newberryi is native to the coastal region of California, in marshes and lagoons with brackish water, predominately in waters where the salinity is less than 12 parts per thousand (ppt), but has been documented in waters with a salinity of 42 ppt. E. newberryi prefers water with mild temperatures (8 to 25 °C) and waters with a depth from 25 to 200 cm. These gobies often use thick patches of aquatic vegetation to hide in if threatened or disturbed. The average lifespan of E. newberryi is only one year. Spawning and reproduction is at its peak during spring and into late summer. However, in the southern region of its range where waters remain at a warmer temperature, E. newberryi will reproduce year round. The females lay between 300 and 500 eggs into a burrow dug out vertically by the male, which is 10 to 20 cm deep. Spawning locations are usually located out in the open away from any vegetation. The male then guards the eggs until they hatch, which is 9 to 11 days. Habitat loss and modification are the main threats to E. newberryi. The brackish areas where saltwater and freshwater meet are where they live usually, such as along the coast of California; this area has been altered by development. Barriers such as dikes and levees have been built to protect residents from potential flooding, but the creation of these barriers has reduced habitat for E. newberryi. Other reasons for population declines are attributed to exotic fish and amphibians which have been introduced to the region. Many of these fish prey on E. newberryi, and others outcompete them for food and habitat. The altering of streams flow with diversions has affected the salinity of the water and changed the habitat at creek mouths where E. newberryi has historically lived. Restoration projects have been started to bring populations back to a more stable number by making more habitat available, as well as providing protective areas. Some levees have been removed and exotic species reduction programs are being initiated.