When my cherry barb fry grow up and 'move out'. The tank has to go if i want a gecko in my 15g. I know i'd be aloud to keep it if i got rid of the heater but that really depends. So i have a few questions.

Will Java moss grow well without a heater?
What Fish can live well in coldwater? (Bare in mind this tank is 6gallons)
Is there any Shrimp that can live in Coldwater?