I've been to some ***** around my area too, and like most answers, the fish usually have ick, discolor, or floating like they are going to die.
There was this one time when I was trying to buy some ghost shrimp from *****, which they just arrived. I told the lady that I would like a few of them.
She said that they need to make sure the ghost shrimp survive first, and come back in a few hours. I told her that it doesn't matter, I am only using them to feed my fish.
She looked at me weird, and said, we do not sell them as feeders, and we need to acclimate them first.
Keep in mind that all there fish are floating in there tanks as we speak.
Another lady walk by and open every single bag and put them in there with the water that came with the bag.
I asked the first lady if that is how they acclimate the new fish, and she yes,"We must float them for 15 minutes first before putting them into the tank.
I also ask, are all the tanks connected? she said yes.
I laugh and left.