Can winter kill still happen even it you airate? Had my pond for 9 years and this is the first time i had a large amount of dead fish once the ice melted. The only ones i seen that were dead seemed to be the biggest ones. perch suckers and large blue gill. pulled out at least 15 fish that were dead. Didn't see any signs of live fish but i think it is too early for them to be active up north .