I have an 80 gallon lagoon (4'x2'), and I used to have two, a two-spot bristletooth and a baby yellow. I recently caught and rehomed my bristletooth (see my build thread for the fish trap video if you're interested) because every since the baby yellow was added about a month ago, the bristletooth has been antagonizing everyone else in the tank. Could I have worked at keeping both of them by trying some more tricks? Possibly. But I didn't feel that it was going to lead to a long, happy life for either of them if I tried to do that, given I have a few other bossy fish in the tank as well (a melanurus wrasse and flame angel).