I think Bob Lusk made an important point when he mentioned the size of the pond in connection to diversity. If a pond has a uniform habitat one predator and one forage species will be able to dominate. To have diversity in your fish you need diversity in your lake. If someone wanted Bass and walleye they are going to need to build a pond that offers seperate walleye habitat. Most ponds are built to offer 100% bass habitat. But by adding some deeper holes, sand and rock piles and yellow perch the walleyes can maintain there home court advantage, so to speak.
Bob's other point about maximum carrying capacity is also true. A survey in northern MN found that lake trout did better in lakes with out small mouth bass. SMB generaly use habitat under 20' deep, while Lake trout in northern MN spend the summer near the 100' mark. Yet these species still manage to compete enough that the lakers growth is slowed.
