I think they would work in that size, both those plecos must have a lot of driftwood in the tank to survive. I learned the hardway with a peppermint pleco. I had driftwood, but not enough. Now I have a 3x1 foot peice in my 55 that my gold nugget is always on, I rarely see him on the glass or anywhere else. They also love it if you cut a cucumber in half, microwave it in a wet paper towel for 20 secs, weigh it down and drop it in.