Native American Killifish Summer-Winter rubbing?

[ForteanFish]

Hi everyone, thanks for allowing me in the group. I've already learned so much, but need some help. I live in Northern Virginia, USA for context. I am preparing a 40 gallon outdoor pond tub to be on my deck. I'd like to *try* to make this tub last all year into next winter. For that reason, I'm considering one of the following killifish to tub: Fundulus heteroclitus (Mummichog), Fundulus diaphanus (Banded killifish), or Fundulus chrysotus (Golden Topminnow). However, I'm getting mixed reports if it can be done. I plan to have 2 sponge filters going all year. I was going to out a heater in the winter, but I heard somewhere it could add $100-200 to the electric bill. Could any of these species survive a Northern Virginia Winter in an above ground tub with temps getting as low as the teens farenheit (-11 - -7 C) but mostly in the 20s and 30s farenheit?  If not, does anyone have any suggestions on killifish or what I could do to make this work? Also I'm hoping to keep this a North American Natives Tub.

[OceanTruth]

This might sound horrible, but I would just try it with a small group. The only thing I would worry about is that the tub would completely freeze into a block of ice. I don’t think that is an issue with a couple of sponge filters constantly running though.

Any future generations produced would be much more cold tolerant than the previous one. I don’t have any experience with killifish so I don’t know how hardy they are. I know shiners have a rep of being hardy though.