Yes that makes sense and is mostly right. I do want to point out that natural fertility (normal carrying capacity without feeding or fertilization) varies hugely from location to location. In some ponds 100 lbs per acre is all that can be grown and in some locations over 3000 lbs per acre are carried naturally. It all depends on each location and owners goals as to how , if at all, those goals can be achieved. But you are absolutely right about the concepts. A pond is like a engine , sun, water , nutrients and it produces fish and , plants. Like an engine the longer and harder you push the rpms the more likely it is to break. The more you know and the better you manage it and take care of things the better it runs but it can still break.