Synodontis eupterus

Not sure where to post this, but I guess here is as good as any. I have four tanks and two of them house one of each of these. I have noticed that when ever I try to get duckweed to grow in either of the tanks housing this fish it just disappears in a short time. 1 to 3 days. The other two tanks I can hardly keep it under control it grows so fast. The only fish that is common to the non growing duckweed tanks is the Eupterus. I know they are not supposed to be a veggy eating fish, but can find no other reason for the disappearing duckweed. Since they only come out during the night much and that is when it disappears I was curious if anyone else has duckweed and wants to get rid of it they might try one of these fish. I don't mean they thin it out....The duckweed and any remains are gone completely in a matter of hours sometimes. I'm tempted to move one of the fish to my duckweed infested tanks and see if they can eliminate it as quickly. All I gotta do is catch one of these buggers.8-[