Sometime when we meet I will tell you a story of an unintended experiment I made a few years ago with tap water and small trout.
I remember doing this when I was like 12. We made a dam at the little stream at my grandfathers house, and wanted to stock a trout in it (it was a chub stream, not a trout stream). We were going there the next day.
So we went out to a trout stream, caught a native, put it in the minnie bucket, and took it home. We had a cooler in the garage, all hooked up with air pumps and so forth, that at times my dad used to store minnies. We had let some water sit for a day like you do when you're starting an aquarium, and cooled it some with ice, filled the cooler, and in goes our fishy. Turned on the air pump and all was fine for a few hours.
Then of course, the water began to warm. Fish beginning to visibly struggle. So in goes some more ice, and, too much, temperature shock! Oops. As he went listless we frantically dumped some of the ice cold water back out, and replaced it with warm fresh tap water to stabilize the temps. It lifened up alright, it went nuts! Chlorine from the fresh tap water. So we put some of that anti-chlorine stuff you use in aquariums in, and that calmed our fishy down pretty quickly.
Every few hours we'd fill a bucket with cool water, add a little ice, some of that aquarium stuff, and exchange half the water. Fish stayed alive overnight and was stocked into said dam. Which, of course, was about 75 degrees and it quickly went belly up. Oh well. We got it there.
We proceeded to catch some pumpkinseeds from a nearby farm pond and take them to our dam. That worked better. We actually caught one the next day.
Disclaimer: This was about 25 years ago. I am now aware of the ecological dangers of transporting fish to different waters. And I won't say whether the brookie was of legal length, either.