Ok so for the past 4 to 5 weeks, a couple dead bass and a few blugill have been showing up dead in our pond, the water has been a murky brownish green and never clears up which is weird it used to be crystal clear years ago, So I thought mayby the heat had contributed to the fish kill the pond is 1/2 acre and 8 ft deep, so I go out their this morning and see fish hittin top water it has cooled way down from 90s to mid 50s, so I thought finally they are active. Only to find hundreds of dead fish all the way around the pond, I have dead bass, bluegill crappie, pearch, grass carp, and lots more dieing, I have a light coat of a greenish looking algea on the pond. I called jones fish hatchery this am to ask them if they test water which they said they do not, but suggested it sounds like a blue green algea, which can kill fish. they said when it is hot the algea is more stabil and put off less toxix stuff, but since it has colled down its probly killing the algea and have a lot of toxic stuff in the water, but they could not be sure? So what do you guys recommend I do? I am located in north east Indiana.
Thanks
Jason

You didn't say, but if you're not aerating...you should be!! At an 8 foot depth, if your algae is dying, you have virtually no DO. If you have a means to circulate the surface...outboard motor or something.... I'd be doing that ASAP.

I agree with Mike. As another option you can get a cheap gas powered trash pump at Harbor freight. As an emergency measure set it up on shore and have the output spray onto the pond.

Just find some way to get air and water mixing.

I'm no expert, but the drastic temperature drop and brownish water sure sounds like turnover. As the other posters said, add DO ASAP.

Anthropic is spot on....Water temps going from the 90's into the 50's is a sudden turnover....Sad to say, there is nothing you can do now except wait and let critters clean up the carnage. A turnover is a double whammy on the fish, toxic oxygen depleted anoxic water is on top and mixed...fish are both suffocating and being poisoned. Wait till next spring and fish the pond a LOT with small lures and hooks to get an idea of what survived (some really tough, quality fish will survive) in order to determine what corrective stocking you may want or need to do.

On the bright side, the pond will be an awesome fishery again in 2-3 years for a while.

You might need to install an aeration system. As the other's have said. My fear would be sudden turnover, even a really hardy fish would not survive. Sounds like it's time to start a fresh in the new year! Maybe try a home aquarium whilst you wait?!

It's sudden and happens without any sign. It may happen for various reasons such as sudden temperature change or out of range temperature, bad/stale food, Sudden change of water chemistry, fall in oxygen level and overfeeding. In my opinion, In the present time, you need to verify what the wrong thing happens and then start from the beginning.