Looking for help with a pond.

I have a half acre pond near Steamboat at about 7,500'. Planted fish in it last year and they grew like crazy. Was great until 10 days ago when they all died. Some floated and some sank. Pond had a pretty strong crop of moss but it also has an aerator. There's another on the neighbors property that gets water from my overflow and all his died too, about a week before my dieoff. He has no moss in his pond. Anyone have any idea what would cause this or know who to call? Thanks in advance.

 

I don’t know how to tell. The fish were growing great so there was planet of food. We had fresh water running through it all the time. And we had the aerator. The oddest part is that the neighbors pond that takes our outflow had the die off a week before us?

 

Thanks. I just found a contact for one of the fishery guys and he’s helping me. Will let you know what I find out. How long are you in Colorado?

 

That makes the most sense of anything I’ve heard. But if his pond has no moss/algae, what other sources of toxins are there?

There is a coal mine in the area and a coal fire underground within 1/2 mile. They’ve been working on it lately to try to put it out. Any chance that’s the cuprit?