What kind of fish do you have and how big is the pond (size)? OK above I see the pond is small 40x85 = 0.07ac. Fish are HBG and LMB both fingerling sizes.
Fish species will be an important factor here. Trout require more dissolved oxygen(DO) compared to BG and LMB who need the midrange amounts of DO. Lowest DO is tolerated by yellow perch(YP) and northern pike(NP).

Two weather things will determine the condition of fish under solid ice in Utah. 1. The depth of the snow cover. 2. The length of time the snow deeper than 2" lays on the ice. Your maximum water depth of 5 ft does not allow a large storage volume/amount of dissolved oxygen in the limited or shallow depth of the pond. The deeper the pond and more water volume it has the more DO is present to last a longer period of time in the dark conditions under ice and blanket of snow. One good thing you can do to prolong the DO under complete snow cover is remove around 10% to 20% of the snow from the pond. The more snow that is removed the more DO that is created by the microalgae. This snow removal allows sunlight penetration and the microalgae makes DO to keep the fish healthy. NOTE -- cloudy muddy water reduces light penetration and thus the amount of DO production by the microalgae. Clear water will allow sunlight easily into 8ft - 10 depth of winter water. If the girls want more skating area then ask them to help remove some of the snow if you turn off the aerator. For complete snow cover and 5ft water depth, complete loss of DO which occurs from the bottom up, the adequate DO near the upper 2 ft ""should"" often last 3 weeks, although this depends on the amount of dead organic materials on the bottom. More organics cause faster depletion of DO without ice penetrating sunlight.

The other item that I have discovered with this that has an influence here. You have been running the aerator while the 6" of ice has developed. This has chilled the pond water lower than the normal winter water temp of 39F with ice cover and no aeration. Your pond water should now be around 33F to 35F compared to the 'normal' 39F. Your fish could easily be in 33F-34F water, thus they are 5F to 6 F colder. Everything in this colder water including all the decomposing bacteria will be consuming measurably less DO because it is ALL colder. Also the fish at these lower temperatures will tolerate lower DO before they die due to lower metabolism. Metabolism requires DO. Also small young fish tolerate lower DO than large fish. Old big fish require the most/highest DO. Also it is a new pond with very little organics accumulation - DO will last a lot longer due to low decay volume. So with these four items your DO should last longer before dangerous fish killing concentrations occur; up to 4 weeks, "maybe'' 5 weeks, ""maybe"" 6-7 weeks with complete snow cover. Before then and when the girls have had enough ice skating, you could restart the aerator and open an ice free hole to allow sunlight back into the pond or just keep removing snow for ice skating.

Good luck with this. Please return and up date us on the developments.