A separate tank of barbs would also do.
Our's ate three otocinclus put into the tank. Not an intentional thing....
The oto's were in a smaller tank that just wouldn't stabilize in water chemistry and were starting to show signs of ammonia toxicity. We put them in our 55 gallon, and they perked right up. Then, about 12 hours later, we found them chopped in halves by the barbs. Nasty fish to anything that fit in their mouths. Kind of like Cichlids, but smaller...