Royal Netherlands Institute for Sea Research

Catch of a round goby

Another interesting fish in the NIOZ fyke. This time, a round goby (Neogobius melanostomus). This goby arrived in the Netherlands a few years ago from the Black Sea. It remains unclear whether it came via the Danube-Rhine Canal or in ballast water.

A round goby, Neogobius melanostomus, caught in the NIOZ fyke.

Extra fish species

The round goby has already established its stomping grounds in the south of the country and in Lake IJssel. It is a freshwater goby, which can also live in brackish waters, so we could have expected that it would one day also appear in the Wadden Sea. However, we didn’t come across it until this year. We saw them near the locks of Den Oever during a fishing trip at the beginning of September, and caught a few in April too. We can therefore summise that in 2015, we got an extra fish species in the Wadden Sea.


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 that are fused to form a single disc on the belly of the fish shaped like a suction cup. Round gobies range in length from 4 to 10 inches (maximum of 9.7 inches (24.6 cm)), and in weight from 0.176 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.