Lost fish in dead of winter
 

I about a week ago, one of my fish came up from the bottom and started gasping at the deicer. This behavior was odd as I have never seen it in the 8 years I have had the pond. A few days later the fish was dead at the bottom. The other fish seem fine, but
I am concerned as to what might be going on.

In the dead of winter is there really anything I can do anyways?

Does someone have suggestions what might have (or is) happening?

As the water starts to warm this spring, should I be overly concerned that more deaths may occur? (and is there anything I could do to stop it)??


Thanks.