Too rapid of a temp change in the water can kill them. Like getting 5" or so of snow in a shallow pond........

Fish float when their guts have more gas in them due to decomposition, and then the fish floats. Very few will float right after they die. If that happened, then the fish would have to be constantly swimming to stay down, and when they stopped swimming they'd float to the surface.

Cold water slows down decomp rate. What is your water temp?

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