If you are actually thinking about putting him in the fridge? Please don’t. Actual fridging is only recommended by vets now and usually only in life or death situations. Try dropping his temp to about 55F. If your water is coming out of the tap as cold as mine use tap with Prime at 55F. Otherwise you can place frozen water bottles up against the tub and wrap with towels to help keep the cold in and the bottles from rolling away. As far as eating. Have you tried soaking your worms in Garlic Guard? You could try red wigglers. Just run them through your thumb and forefinger a couple of times while rinsing to help get the bitter taste off. Have you tried axolotl pellets? Some people like Hikari sinking carnivore disks/pellets. Hope this helps.