How about some species of salamander? Most prefer cool temperatures in the 60F to 70F range. I've had a tiger salamander for almost 10 years. He might have only cost $10 and he might not be bright blue or orange like some of my other amphibians, but watching him down a leaf worm or cricket is something else. There are many other species of salamanders to look into as well. You might want to visit www.caudata.org and see what they have to say.
Otherwise, as far as frogs go, your selection will be more limited. Most of the commonly available frogs that you'd find at your local pet store require warmer temperatures. Fire-bellied toads tolerate cool conditions well however some sort of supplemental heating will probably be required to premanently keep them. The cage can be heated easily with a low wattage light bulb if needed.
Yes, you will have trouble keeping some feeder insects. Crickets will not survive for long at those temperatures and will either need to be kept in a warmer room or have their cage heated. Wax worms, mealworms, leaf worms and night crawlers should do fine at those temperatures. Good luck,
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Devin Edmonds
devin@amphibiancare.com
www.amphibiancare.com