Thats just speculation though isn't it ? both that the LFS might have advised the buyer, and that he would have lied. It does not change the fact that if the LFS's had a display card for each type of fish with relevant info, it would be a useful service to customers, of potential benefit to the welfare of the fish they sell, and would also cover their butts in scenarios such as this one, where they might be considered in part to blame.