monkey goby, funny and curious freshwater fish species, swim to catch insect prey, highly adaptable, european southern bug river

neogobius fluviatilis fish temperate river brackish endemic rare nature water clear young natural aqua biotic animal aquatic harmful destructive fishkeeping underwater weed decorative omnivore closeup tank gravel local native wild mouth lips predator biotope aquarium sand ecology threat unusual fauna widespread deathly pontocaspian aquadesign nano swim wildlife controlled conditions environment glass refraction