I think the topic of whether puffers can be with other fish will never be agreed. My two green spotted get along with my Mono's and my archers, but i have read that personality and age can be a factor, it said when they get older they can suddenly change from being ok with other tankmates to ripping apart everything that they can find, but again they can just stay being friendly. Ive had no trouble with fin nipping, ive even had mono's and puffers eating a mussle face to face without any trouble. so maybe is just luck, it seems there are good and bad stories for both sides of the debate.