Thats not a lot of room, maybe if you said 50 gallons with lots of water changing.
I have a 34 gallon that i want to use for a pondfish thats around 6 inches and im thinking its going to be too small.
Could you get a large tub that holds the 50 gallons and then place the filter in that?
yeah, I think the tank is too small too, even for just the winter. I would do as fantail suggests and get a tub. A UGF and powerfilter won't be enough to sustain this, their growth may stunt and your water changes would have to be daily to say the least.