Round gobies (Neogobius melanostomus) are some of the most invasive fish out there))) And I have a small colony of them in my Dniester Biotope. Despite only being in captivity for 2 months, they have spawned. The two males have turned dark (which is their breeding color) and are spending most of their time in the caves. Probably guarding the eggs or young fry. There also monkey gobies (Neogobius fluviatilis) with them, but I think they are all females.
