Man it sounds like a vicious circle!!?? or is it cycle??? same difference, isn't it?? (favorite saying of an old buddy) Yea, we fertilize to create plankton, and we aeriate to save our fish from algae overbloom (filamentous algae that is) The main thing to remember is that its all a matter of timing-timing-timing. You can either hire an experience manager or become one yourself through trial and error!! If you know someone at your local wildlife and fisheries office they may be talked into doing an electroshock survey, or you can sein a portion and have a biologist identify each fish by species and age to get a sampling of your pond diversity. None of this stuff comes easy. I'm sure you will get more helpful advice!