One other thought. Overfertilizing a pond can have disastrous effects. If you have a highly fertile pond and get 4 or 5 days of heavy clouds and no wind, the plankton base consumes more oxygen than normal resulting in a dissolved oxygen crash. The result is a fish kill that usually starts killing the largest fish first. I've had 2 of them and now am a very cautious fertilizer.
This is, I expect, why Shawn recommends checking with local authorities.
