I disagree with that statement. From wholesalers they often only get a 24 hour guarantee, which they can institute upon taking the fish.
Harley,
This is how I went about it... The closes LFS to me at first would not give me any credit for fish, even though I spent hundreds there monthly, sometimes thousands. When they refused to give credit, I stopped shopping with them for a couple of weeks, and when I went back I asked them if they would take the fish for store credit and they did. I wasn't trying to press them, but there were other stores that would at least give a helping hand.