If it helps any, some fish stores have critter keepers. They look like this:
They sell them for pretty cheap at a fish store near me, like a 5 gal for $15 I think? There's usually some heaters you can get for them too. I noticed that there's no place for him to hide in the tank you have now, I would try and get a silk plant if not a live one to help comfort him.
Also, if you have like a WalMart near you, you can get a Tupperware bin by rubbermaid or something. I used that for a temporary bin while I had my bigger tank cycling for my Bettas, they work great! Cheap too. Can get like a 3gal one for a few dollars, possibly cheaper than the critter keeper.