Identification
The tubenose goby is the smallest of the three Ponto-Caspian gobies in the Netherlands, reaching 8 to 12 cm. The body is slender and light brown with a characteristic marbled pattern of dark spots — hence the Dutch name "marmergrondel." The most distinctive feature is the tubular nostrils that protrude above the upper lip like small tentacles. The head is relatively small and rounded. Like all gobies, it has fused pelvic fins forming a sucker disc. The difference from the other gobies: the tubenose is smaller, slimmer, and has the conspicuous tube-shaped nostrils.
Behavior & ecology
The tubenose goby is a bottom fish that lives among stones, riprap, and bank vegetation in both flowing and still water. It feeds on small invertebrates: worms, midge larvae, amphipods, and snails. The species is less tied to hard substrate than the round goby and is also found in softer habitat — transition zones between river and polder. During spawning, the female attaches eggs under stones, which the male guards. The tubenose goby originally comes from the lower reaches of rivers around the Black Sea.
In the Netherlands
The tubenose goby is the third Ponto-Caspian goby species in the Netherlands, alongside the round goby and the monkey goby. It was first recorded around 2002 and occurs in the major rivers and their branches. Of the three invasive gobies, the tubenose is the least abundant and least aggressive. Its impact on native bottom fish is likely smaller than that of the round goby, but the species does occupy the same hiding spots as the protected bullhead.
What our models found for Tubenose goby
Below is what our models see in the data. These are links: where one thing occurs, the other occurs more often. That is not a cause. Each model answers one question and may not say more than it measured. The label by the heading tells you which question — and how sure the answer is.
Where this species lives Strong model
Bitterling (Rhodeus amarus)The asp comes first, then the bitterling, the ide and the spined loaches. That is a mixture: asp and ide are river fish, while bitterling and spined loach belong to still, weedy corners.
That combination fits a fish of the slack water ALONGSIDE the river: old arms, harbours and overgrown banks, right next to the main water.
Further down sit American crayfish (Cambaridae), the bleak, valve snails (Valvatidae), the Asian clam (Cyrenidae), opossum shrimps (Mysidae), Bithynia snails and water mites of the family Unionicolidae, which live inside freshwater mussels. Organic matter and nutrient level count too.
Note: we hold two tubenose gobies in our data and they carry the same name. The other column is a feature in THIS model, which makes the species appear to predict itself. That is down to our naming, not to the fish.
