Wanted to buy oysters, fish monger couldn't help

Approached the fish monger at the fresh fish station to buy oysters, he rep**** by saying he could only give me the price and that he did not know the difference between live and dead oysters and said I would have to do it myself. If he can't sell the oysters, why are they there to begin with?. Please consider training your staff in the products they sell if not anything else.