RES can and will die from lack of DO under the ice, however I don't believe they are any more susceptible to this than BG. The issue as RC51 eluded to is the temperature. RES are southern fish, with their native range barely making into the southern 1/4 of Illinois. Even there, they were naturally uncommon that far north. In northern areas, RES tend to do best in larger bodies of water where the water volume can regulate rapid changes in water temperature which I believe is the biggest killer of RES. They just can't handle fast swings in water temperature. Larger bodies of water take longer to warm and cool and thus help prevent these swings. Deeper bodies of water also help with this. If your pond has a fairly large area with deeper water, the RES can stay in that area. Water is most dense at just above 39 degrees F. This is right around the minimum temperature RES can tolerate for extended periods. When shallower waters begin to cool so much that the 39 degree refuge begins to cool, I think that is when RES struggle. You can also see this super cooling occurring in ponds that are aerated, especially incorrectly.
Last edited by Bill Cody; 01/26/26 07:52 PM. Reason: spelling correct
