Actually, Sparkie, tilapia interrupt the vicious cycle. They consume algae, converting those nutrients into flesh, then consumed by other fish.
I've got one client in particular, who is way over the top when it comes to pushing his lake. I worry about water quality all the time, especially during the hottest months. This lake is collecting way too many nutrients. We monitor water chemistry bi-monthly, and nitrites continue to rise...until we add tilapia. We're trying to wrap our brains around that, too. Here's what I can tell you. In lakes where trophy bass are the primary goal, tilapia increase survival rates of young of the year bluegills. More bluegills feed more bass, escalating growth rates of remaining bluegills. Tilapia play a key role in both bass growth rates (and I'm about 80% convinced that tilapia aren't a primary diet source for bass, but by increasing survival rates of YOY bluegill, tilapia indirectly are responsible for significant food for bass) and bluegill growth rates (bluegill, as YOY survive, add to growth rates of bass, which helps support bigger numbers of big bass, which cull more bluegills of specific size classes). Here's a summary of my opinion about Tony's great question. Tilapia increase survival rates of YOY bluegills, which adds to the food chain of largemouth bass, which adds to growth rates of bass, which increases the sizes of bluegills that bass eat over fall and winter months, which increases overall sizes of surviving bluegills.
Sounds complicated...which it is. But, simply, more food in a different niche adds more food to predators, which increases average size, which increase mouth size, which increases prey size, in a perfect pond world...which doesn't happen.
So, forget about what I just wrote and do what works best for you.
