Some other thoughts in addition to the outstanding discussion above.
As Dave said, although expensive, the fish are usually one of the cheapest parts of the whole project. The best comparison I can think of is the landscape industry. We are talking about laying turf as opposed to seeding a lawn, planting tall $500 trees rather than young $5 trees. Compared to the cost of the house, or in our case, lake, it might sense to stock adult fish ready to go.
There is a huge problem with stocking adult fish...in general, they're not available. Why should a hatchery keep fish to a larger size when they can sell them at a profit when they are small? Except for a few high value species such as sterile grass carp, SMB, HSB or easy to raise species like CC or trout, I don't see this happening. We are then forced to get fish from other sources.
If we want to add another species to our existing lake, we are forced to stock adult fish. They have to come from someplace and if hatcheries aren't raising them, where?
Depending on the area, many fathead minnows are caught in the wild. Stocking fathead minnows in many cases is no different that going out to the local river and putting these fish into our lakes.
