I agree with most everything that has been said above, with the exception of the opinion expressed that huge bass can't be grown in small water.
Years ago I used to work with a very narrow pond that could be cast across in most places along its length; I would be amazed if it were an acre total, though it was probably a tenth of a mile long at least. It may have been an acre...But it had some HUGE bass in it. That's the only body of water I ever fished in which I had more bass break me off than I landed; I'd go so far as to say it was the norm rather than the exception. It was an old phosphate pit, had been stocked more than sixty years prior by TVA after they finished mining the area; the first time I ever fished it I caught ten to fifteen (this was twenty-two years ago) bluegill that would have averaged 12 ounces or better. And almost every time I fished it for bass, it was an exercise in heartbreak; the pond was full of wood, mostly trees that grew in the water but also a good bit of fallen timber; I would throw a plastic worm around some of that cover in the deeper portion of the pond (which was only around six feet, perhaps eight in a couple spots), get a hit, hook a fish that made a washtub-sized boil or two, the fish would strip off line and hang me up, snap the line and leave me wondering just how big a bass can get in TN, and why I wasn't using heavier than fourteen-pound test. This happened numerous times in several different spots in the pond.
Greg is right in that you can't grow as many large fish in a smaller body of water; that's true with any species; there's just less total oxygen, less total plankton, less total invertebrates to feed the bluegill, less carrying capacity. But you can grow a few bass to monster size.
If you have the capability to enlarge the pond, you can always, always do more with a bigger pond than a smaller one. But don't go deeper; unless you install an aeration system, the deeper water won't be used by the fish for much of the year due to the thermocline, and can actually cause a fish kill if the pond turns over. The way to expand is outward, not downward. Inundate new ground and you directly increase the carrying capacity of the pond.
