|The Range of the Round Goby|
Round gobies are small, soft-bodied fish, characterized by a distinctive black spot on the first dorsal fin. Their eyes are large and protrude slightly from the top of the head and, like most gobies, round gobies have pelvic fins which are fused into a single pelvic suction disc on the belly of the fish. Round gobies range in length from 4 to 10 inches (maximum of 9.7 inches (24.6 cm), and in weight from .176 ounces to 2.816 ounces, increasing as they age. Male round gobies are larger than females. Juvenile round gobies (less than one year old) are grey. Upon maturation, round gobies become mottled with gray, black, brown, and olive green markings. Adult male round gobies turn inky black during the spawning season and develop swollen cheeks. Male and female round gobies are easily differentiated through the shape of their urogenital papilla, which is white to grey, long and pointed in males, and brown, short and blunt-tipped in females.
Widspread in the Sea of Marmara and rivers of its basin. In the Black Sea and Sea of Azov along all coasts and fresh waters of their basins. In the coastal lakes and lagoons. In the rivers of Crimea and Caucasus: Mezib, Pshada, Vulan, Kodori, Çoruh. In the Caspian Sea presented by subspecies Neogobius melanostomus affinis. Since 1990 the round goby registered as introduced in the North American Great Lakes as an invasive species.  and different parts of Europe.
Round gobies are euryhaline (salt-tolerant) and are found in both freshwater and marine ecosystems. In habits the water with mineralization of 18-24%, presented in fresh waters. Rather common on shelfs with sandy and rocky bottoms with low silting, on the depth from 1-2 to 10–17 m.
Round gobies usually feed nocturnally (but have been observed to feed diurnally as well) and are believed to detect prey only while stationary. The primary diet of round gobies includes mollusks, crustaceans, worms, fish eggs, zebra mussels, small fish, and insect larvae.
Adult round gobies feed mainly on mollusks. At spring, the main items in its diet in the Sasyk Lagoon are Hydrobia, Cerastoderma, Abra. In the same season near the Romanian coasts of the Black Sea the round goby feeds on polychaetes, crustaceans (Idothea balthica, Pachygrapsus marmoratus, Xantho poressa, etc.) and juvenile gobies. Near Sevastopol the round goby feeds on molluscs (Mytilaster lineatus, Abra spp.), but near Karadag except molluscs (Cerastoderma, Brachiodontes) were fishes.
In the Gulf of Odessa in the diet of the round goby are 23 items. Mytilus galloprovincialis, Setia pulcherrima, Mytilaster lineatus, Lentidium mediterraneum, Idothea balthica, and Alitta (Nereis) succinea dominate in spring. In summer are mainly Sphaeroma pulchellum and L. mediterraneum. Mussels M. galloprovincialis and M. lineatus have big importance in the diet in all seasons. The polychaetes are most elected component of benthos.
Round gobies exhibit male parental care. Females can spawn up to six times during the spawning season, which spans April to September. Males will migrate from the deeper water, where overwintering occurs, into shallower breeding grounds during the beginning of the mating season. The males are territorial and will guard nests of eggs and newly hatched young, resulting in successful hatch rates of up to 95%. Its eggs are 4 mm by 2.2 mm in size. Female round gobies reach sexual maturity in 1 to 2 years while males do so in 3 to 4 years. Gobies in the Laurentian Great Lakes typically mature up to 1 year earlier than in their native habitat in Europe. The male releases a steroid sex pheromone that attracts females to their territory. The male may also use visual displays, such as changing its color from beige to black and its posture, along with sounds, during courtship. The females deposit their eggs in male-guarded crevices between rocks. Egg clutches can contain up to 5,000 eggs. Males defend these eggs from predators, and continuously fan them to provide the developing embryos with oxygenated water.
Invasive species 
The species was accidentally introduced into the North American Great Lakes by way of ballast water transfer in cargo ships. First discovered in North America in the St. Clair River in 1990, the round goby is considered an invasive species with significant ecological and economic impact; the consequences are quite complex as the fish both competes with native species and provides an abundant source of food for them while consuming other invasive species. In other words, the round goby behaves much like most biological invasive controls. An aggressive fish, the round goby outcompetes native species such as the sculpin and logperch for food (such as snails and mussels), shelter and nesting sites, substantially reducing their numbers. Round gobies are also voracious predators of eggs of native fish, many important to the angling industry. The goby's robust ability to survive in degraded environmental conditions has helped to increase its competitive advantage compared to native species. Many native predatory fish such as smallmouth bass, largemouth bass, walleye, salmon and trout have begun to prey on round gobies. These game fish feed so heavily on the abundant gobies that a bait company, called Culprit, has created a soft plastic bait called the "Great Lakes Goby" to exploit this behavior. The incorporation of the round goby into native foodwebs, coupled with the goby's ability to consume large numbers of invasive mussels (zebra and quagga), may result in greater bioaccumulation of toxins such as PCBs higher in the food chain, since these mussels filter-feed and are known to accumulate persistent contaminants. However, this is partly beneficial because even though they do not reduce the population of zebra mussels, they do control their population. Hence, it prevents a large scale spread of the zebra mussel, which is also an invasive species in the Great Lakes.
An unintended benefit of the round goby's introduction is that the Lake Erie Watersnake, once listed as a threatened species, has found it to be a tasty addition to its diet. A recent study found the introduced fish now accounts for up to 90% of the snake's diet. The new food supply means that the water snake is now staging a comeback.
The round goby is also considered invasive in parts of Europe. The processes of invasion of the round goby in Europe were started by its introduction to the Gulf of Gdańsk (Southern Baltic Sea) in 1990. Recently the cases of the round goby invasion are mentioned in the Aegean Sea, in the different parts of the Baltic Sea, North-Sea basin, and basins of the rivers Danube and Rhine. In the German part of the Baltic Sea this fish was first noted near the Rügen Island. Now it is distributed along all south-western Baltic Sea coast includes the Stettiner Haff (Szczecin Lagoon), the Unterwarnow (the Estuary of the Warnow River), the mouth of the Trave River, and in the Nord-Ostsee (Kiel) Kanal.
In total, 88852 parasite species are registered in the round goby in the native area. Most abundant parasites of the Black-Sea round goby are metacercariae of trematodes of Heterophyidae family, such as Cryptocotyle concavum, C. lingua, and Pygidiopsis genata. The trematodes C. lingua and P. genata can infest human. In the 1950s, along the coast of the Gulf of Taganrog (Sea of Azov) the round roby was registred as a host of epizootic of nematodes, Tetrameres fissispina and Streptocara crassicauda, which were fatal to ducklings.
In the Gulf of Gdańsk, Baltic Sea, the parasite fauna of the invasive round goby consists of 12 species. The core of the parasite fauna comprises two species of trematode metacercariae: C. concavum and Diplostomum spathaceum. Also, in the Baltic Sea the round goby is paratenic host of the invasive nematode Anguillicoloides crassus. In the Vistula Lagoon, the most abundant parasites of the round goby are nematodes Hysterothylacium aduncum and A. crassus.
25 species of parasites are noted in the round goby in the Great Lakes. The trematode D. spathaceum is most abundant core species overall. Also the cestode Proteocephalus sp. and the trematode Neochasmus umbellus are rather abundant. The round goby may circumvent more of the metacercariae of N. umbellus from completing their life cycle. The parasite “load” on the invasive gobies in the Great Lakes appears relatively low in comparison with their native habitats, lending support to the "enemy release hypothesis".
See also 
|External identifiers for Round goby|
|Encyclopedia of Life||218104|
|Also found in: FishBase|
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- Die Schwarzmundgrundel erobert den Nord-Ostsee-Kanal
- Round Goby Phylogeography
- Round Goby, an invasive species in the Great Lakes
- Alpena National Fish and Wildlife Conservation Office
- American Fisheries Society
- Aquatic Invasive Species-Minnesota Sea Grant
- Global Invasive Species Database
- Harmful Aquatic Hitchhikers
- Minnesota DNR
- Round Goby/Fish of the Great Lakes by Wisconsin Sea Grant
|Wikimedia Commons has media related to: Neogobius melanostomus|
- InvadingSpecies.com, Ontario Ministry of Natural Resources and Ontario Federation of Anglers and Hunters
- CRS Report for Congress: Harmful Non-Native Species
- USGS Non-indigenous species
- Species Profile- Round Goby (Neogobius melanostomus), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Round Goby.
- Culprit-Great Lakes Goby
- World Conservation Monitoring Centre 1996. Neogobius melanostomus. 2006 IUCN Red List of Threatened Species. Downloaded on 4 August 2007.
- University of Michigan Museum of Zoology. Animal Diversity Web. Neogobius melanostomus. Downloaded on 18 May 2009.
- GLANSIS Species Fact Sheet