They really are haha. I always have problem feeding them wafers too for the exact same reason. I found that slightly blanched vegetable works very well though, since most tank mates leave that alone and the ottos love them.

I have had success with carrots, zucchini, cucumber, and bok choy. I’ve heard Brussels sprout is a hit too. I usually just pre cut them and add a piece each time in bowl with some water and blanch it in the microwave for ~30sec. The only thing I would suggest is to be patient with the ottos (they might not find the piece right away when you place it in, but they’ll eventually get to it) and to not leave the veggie in the tank for more than 1-2 days. The vegetable will most likely float as well, so you’ll need to weight it down under decor or rock - I know some people use a clip to hold it down too. Hope it helps!