I put together a minnow tank, made out of an old 7cu' (apartment size) chess freezer. Got an adjustable thermostat from amazon; where I can keep the water in the mid to low 40s??f. A backyard pond aerator/filter combination. Goldfish food and some chemicals from the pet store to help manage the bacteria. I've kept them for approx a month with very little die off.
I throw the tank in the back of the truck, when we head up to Elk Lake, for a week at a camp that doesn't have minnows. The closes place that do have, is approx a 2 hour round trip. On the way up to camp, we stop at that bait shop and buy 20 or more dozen. The bait shop fills my tank with water from his large tanks; no temp shock for the minnows. Fire up the generator, set the temp, turn on the aerator and off we go.
Before anyone says anything; yes you can share a bait tank will other people. I've checked with the ministry and they said as long as there are enough people there that can produce a recite for their purchase; its fine. We tape the signed recites to the lid of the freezer and never had an issue when a CO shows up at camp.
Dan.