Boogiechillin when I was considering putting a Batfish with my other fish the puffer was the one I was most concerned about. Although I find my green spotted puffer to be quite passive. He does not bother the monos at all, he simply ignores them, and he is already over a year old, so not a juvenile anymore. The monos ignore the puffer as well, although they do nip at each other. Do you think that they might harass a batfish?