My LMB are looking pretty bad. Pulled a dead 17" fish off the 2-acre pond yesterday and may have quite a few more right behind him. He didn't show signs of disease except for a 0.25 inch tear along the lower jaw with a small piece of skin hanging down.

I'm seeing pink lesions on the sides of the fish usually on the gill plate or right behind the pectoral fin. Also seeing the pectoral fin reduced to a thin pink bone. Also seeing lesions on the mouth, usually on the bottom but sometimes on the top near the tip. I'm guessing that it is currently affecting 5-7 of my estimated original 25 LMB. Some of the fish have a clean notch out of the caudal fin. The younger recruits don't appear to be affected. The larger fish are what is left of my original plant (3-years old). The fish continue to feed well.

The only changes in the pond that I'm aware of are the 125 BG added April 16th. We found 3-4 of those fish dead within two weeks with a white fungus. I recently saw another with a sponge-like yellow growth on his side that plastered the pectoral fin to the body. We have one brood of geese (5 goslings) since May 14th. The heron continue to wreak havoc and I originally thought that some of the lesions were due to near misses but I no longer think this is the cause.

I don't have the knowledge or experience to diagnose the problem. My theories include:

1) fin/mouth rot from a decrease in water quality or pathogen brought in with the BG
2) stress from spawning (normal attrition?)

I could catch and photograph a couple but have not wanted to further stress the fish

Can you medicate fish chow for fin rot?

Is there any specific water quality parameters that I should monitor.

Any ideas would be appreciated.