As well, something learned "old school" which I see a lot even in pet shops, is using toxic cleaners in the are near fish tanks (glass cleaners) smoking so on. All goes into the water and harms fish. Here is a major aquarium with just such concerns and the vibrations are not even ...
Myriophyllum, Ceratophyllum... would work> It hadn't occurred to me that the use of media would protect the breeding fish. <Oh yes... easier to be driven into than the pond edges> In re: culling the herd: To those who plan to do that: Don't name your fish. Then...