I keep a single flowerhorn in a 75. He's been in there by himself for about 2 years. He's in a fairly high traffic area. Funny thing is that lately he's been hiding a lot more (I made a spot for him with a flower pot and some driftwood). He's also gotten kind of jumpy at times and seems to get spooked. I also noticed that he now decided that he despises light any brighter than normal ambient day light. The only light I have on the tank now is a low watt single led bulb that just provides just a tiny bit of light. If you're looking for personality, nothing beats an oscar in my opinion.