After dropping an underwater camera in the pond I think all of my perch and walleye have died. I talked with the biologist that was going to test the fish and he concluded that I had a DO crash. He thought testing the fish would be a waste of money. (about $1000) I could possibly buy into that therory, except for the fact I found new dead fish over about a 7 day period and minnows also died and as of today continue to die. Any sort of toxins that would have gotten in the water would have killed other fish also. I was told to test the water we've got to have something to test for.I think I'm going to get about a dozen perch that are pellet trained and put them in the pond and see what happens. The water temp has dropped quite a bit and should hold more oxygen. I think I'm going to start looking for an DO meter so I can monitor things better next year, Any suggestions?