the reason they put worms in the frig is to slow down their digestion and there for produce less waist. that is why your LFS keep black worms in the frig. It helps them keep them fresh longer and slows down there digestion and they dont have to clean them as much. With worms like blackworms, they live in water, but that water can get very dirty fast. So slowing their digestion down keeps them from having to change their water as much and keeps them fresh longer till they get them sold.
I myself raise my own blackworms in a 10gal tank and also raise my own earthworms in the tubs I was telling you about. The earthworms are not alot of work. really easy to keep. Just have to sift there dirt around once a week and feed every other week vegies and stuff(at the least). We eat alot of salad, so I usually when Im making a salad with dinner, cut up a few extra cucumbers and take some lettuce and throw in the buckets real fast.. even thow in some tomato and whatever vegie in putting in my salad at the time.. carrots etc..... (watch how many tomatoes you put in though..they rot fast and can attract nats.. )
the blackworms I raise are more work. Water changes every 3 days and feed flakes and crushed pellets once a week. Its keeing up their water changes is the work since I have to do like 60% water changes to make sure it stays clean for them. you cant vacume the rocks or have a hanging filter due to it will suck them up and the babies up. So all you can use is a sponge filter and do water changes alot...
but to me its worth it, my rays, aro and my ghost shrimp(which I also raise in a seperate tank) love them. It was really easy to start, but is some work.
So if you start a worm farm someday, the earthworms are easier to do. That way you know what they eat and are in control of what they get. and saves money.
If you want though, get earth worms, cut a few up and put in a container in the frig. Add some tank water and add shrimp or whatever..
this way the shrimp will soak up the smell of the earth worms and can help get the rays eating the shrimp and whatever else you soak in the bowl overnight...
oh ya, worms will eat in the frig.. but very little. since the cold slows everypart of them down, they dont eat as much either. worms like it warm, even worm that live in water.. cold slows them down and also slows there digestion.. there for they dont eat like they should...