freshwater and brackish water snail - theodoxus fluviatilis

fresh water scenery scenic scene neritimorpha cycloneritida aquatic gastropod mollusk neritidae nerite snail river macro aquaworld colorful nature macedonian macedonia european theodosius fluviatilis oldest lake underlake freshwater underwater ohrid theodoxus ecology clean closeup infection ecosystem planeria turbellarian planarian planaria wildlife tank exotic animal helmet shell tropical aquarium neritina fauna natural small devour detail flatworm predator worm aquascape trouble invertebrate invertebrates inverts invert dive common name species brackish gill operculum family nerites