I recently lost a fish

which leaves me with an empty 1.5g fish tank. And while my first impulse is to run off and buy another one, my future is kinda up in the air right now (might have to move to another province at some point) so getting another fish to add to the 8 that I now have would be really bad fishy parenting, I think. But that still leaves me with an empty tank, and two fish who would benefit from being moved into it.
So I have to make a decision...do I put the fish who's on the filter side of my divided 2.5g betta bow in the empty tank, or do I put the fish who's in an unfiltered 1.75g bowl in the empty tank?
I'm kinda leaning towards moving my guy in the divided betta bow into the empty tank because he has very little surface area, but then I think of the little guy with no filter. Drat...
Opinions anyone?