The main problem with Walmart fish, is that the people taking care of the fish usually have no idea what they are doing themselves. I am part-timing at Petco at the moment, and nobody there knows much either. They all defer to me, and I get lots of people coming in talking about the awful advice they were given by another employee. It really is unfortunate.
I have asked the manager to stop carrying iridescent sharks, she agreed, but they continue to come in. I think she is too lazy to change the order.