Need ideas

Some of you may know i got a 150G a few months ago. The only place it can go is in the garage though and with temps how they have been recently its going to cost around £700 a year just on heating which is to much atm. Its well insulated and im still going to keep 300w of heater in there so it will still stay around 10c in the winter. So i need ideas on something that will work at 25c in the summer and down to 10c in the winter. So far im thinking a shoal of Perch or a group of Channas and then once they pair get rid of the other 2 and breed them or if not im thinking about selling this tank and my other 3 and moving onto reptiles probably a Berber skink or Blue t ongue skink if i can get the money. Any ideas?

Cheers

Well ive decided im going to give up on the 150G and probably sell it and just keep the 30G and change the stocking instead.
The 30G is going to be an Catfish only Asian biotope with
3 Akysis vespa
3 Akysis prashadi
15 Kryptopterus minor
5 Mystus bimaculatus