Can you take a picture of the pond? What kind of fish are in the pond? How many fish are there? Before I could help you, I'll need answers for those questions. You didn't give any dimensions on this pond, nor a depth. That will have a lot to do with what corrective action I'm going to recommend that you take.
I'd also like to know if it gets a lot of sunlight, or is in a shady area that only gets a few hours of direct sunlight per day. The more info you give me, the better the advice will be that I wind up giving you.