Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations dying fish

We have a 2 acre pond in south central IL. Over the last week we have been losing about 15 fish a day. Most of the fish are adult bluegill. We have also found 2 bass and one bullhead(which were not stocked, but somehow found there way in). We have a fountain that we run year round and we feed our bluegill. The dead fish have no visible marks on them and they do not appear as though they quit eating prior to their death. Our pond is bordered by a field, but we have no more than 5 acres of runoff from the field and the field has not been treated yet this year. We'd appreciate any advice or answers. Thanks,
Mike

Are you sure no herbicides or pesticides have made it in somehow no matter how far away? With all the rain we have had anything sprayed on fields can go a long ways.

any sign of fish on surface gasping for air?? if so could be oxygen depletion which can kill fish - however I believe when that happens it is a sudden die off as opposed to a few fish dying at a time. I lost all my fish some years back due to sudden cooler weather following a drought and the lake turned over and my fish died from lack of oxygen.

Thanks for your replies. No fish have been gasping for air and I know no herbicides have been applied yet this year. Naturally pollutants were my first thought, but now I'm wondering if it could be some sort of virus, bacteria, etc. because it has mainly targeted adult bluegill 6-9 inches.

this may sound stupid but cut the fish open and check for fire ants. its not uncommon around here for ants to wash into a pond and get eaten up by BG. they die from the bites they take internally. also check the gut cavity for parasites, environmental conditions may have caused an outbreak. not much you can do about parasites. stocking shellcracker help keep snail populations down which play host to many pond parasites.

drop me a personal email and I can shoot you over a autopsy based condition assessment paragraph from one of my books.

Shan, thanks for the suggestion. Fortunately our fish stopped dying so I haven't been able to check them. I appreciate your reply.

Mike