Iowa 1.5 acre pond, 2.5 years old channel cats, redear, fhm, lm bass, hybrid bluegill, crappie, windmill aeration


we had a hard winter, never lost my aeration hole but had up to 20" of ice on most of the pond, ice just got off yesterday, only one dead redear floating

my question is--- did i survive winter that well or did fish die and sink? will winter kill fish sink and disappear? how can i be sure i came through such a brutal winter, i had more die than that last year but they all floated

i had an otter for about 2 weeks last fall and i hope he didn't do too much damage before he moved on, but i was expecting to see some floaters this spring