duckweed eradicator ???

Can anyone suggest a method of eradicating duckweed? It thrives in my
tanks far too well. I routinely remove a layer off the surface of the
water with my weekly water changes. Are there any fish (or other creatures)
that are natural predators, that won't do too much damage to my other
tank occupants, bith plants and fish?

Eric Deese   Columbus, Ohio  USA