As an ex-peacock bass keeper I had things end with the same luck as most. The fish died. One being the exception. I'll discuss why I think it's still alive today later.
Peacock bass from my experience are not territorial. They actually seemed pretty laid back unless it was large enough to fit in it's mouth. Which is surprising what won't fit. They are cichlids and do get very large in the wild. From what I understand there are a few color variations of peacocks. The ones usually sold in the pet trade are the lighter brown ones that from my experience never delevope into the beautiful green and red one caught in the wild. A few of the ones I kept however do get colorful. Just nowhere close to the ones I've seen caught on fishing shows, in magazines, and the internet.
As I mentioned before all of the peacocks I've kept end with the same fate except one. All of them died at around 10 inches. The one that did make it has since been given to a friend that moved to florida. He houses it in an outdoor pond in his back yard and tells me it's up to around 15-18 inches now. I believe most of these fish fell to the same fate simply because of the diet offered. I experimented with all of these fish while I owned them and the one that's still alive had a much better diet than the previous fish. All but the one that made it ate only goldfish and guppies. The survivor was offered a larger assortment of live and prepared foods. It was actually the only one that would accept prepared food which consisisted of pellets. It also had a larger range of live food than the others did. I offered it crayfish, mosquito fish, guppies (which I raised), goldfish (which were born and raised in on of my ponds), ghost shrimp (caught locally), small catfish, frogs, bait lizards, and on a few occasions is even got a live eel when I could find one small enough at the local bait shops. I believe it lasted longer that the others simply because it's diet was closer to nature than the previous fish. Feeder goldfish and guppies purchased at your lfs are usually diseased and weak nutritionally. I believe the diet is the key to keeping these wonderful fish and if it's not possible to offer them a varied diet of quality food they slowly die because thier nutirtional needs are not met. I'm no expert. Far from it actually. But the last peacock I raised seemed much healthier, growed faster, and by far was more colorful than the others I fed just feeder goldfish and feeder guppies.
I'd suggest if you purchased one to please consider how big it will eventually get if you can keep it alive. If you do not have a large tank, indoor pond, or outdoor pond that could be kept at the appropriate temps I suggest you not purchase the fish.
If you have any more questions please feel free to ask. Like I said I'm no expert on these fish but have kept a few over the years. It was one of my favorite fish. And probably the most expensive to feed.
Vaheelsfan. What's the name of the pet shop you mention and where is it located? I'd like to visit some day just to see what they have. Maybe I'll find a unique addition to one of my tanks. I also have heard about a great store in Lynchburg... But can't remember the name or the directions I was given.