Mine likes apples. I was eating one and I dropped a tiny piece in there and she ate it. lol. I put pumpkin in my tank but it floated and went rotten so I took it out because nothing was eating it (got platies and mollies in there as well as the bn, none seemed too interested.) I also get algae in the tank, and I clean it off the front glass for purposes of appearance, but I leave it one the back and sides so the bristlie can eat it. She's always hanging off the glass munching algae.
Mine was really timid when I first bought it, but it's less scared of me now, and since I got rid of the biting molly she comes up to the surface and grabs the odd floating pellet and takes it down and eats it.
Reckon they'd go for potato? I haven't tried that yet.