I'd suggest informing him that you'll be relating your experience and the name of his store on this forum. I've had that change more than one person's mind about taking a return. Now, if he didn't know how big your tank was, that may be another matter. A responsible owner would have asked, but that's more of the exception that the rule I'm afraid. Either way, he obviously doesn't care for the welfare of his fish, so I'd look for another LFS or like you said, someplace online. Liveaquaria.com seems to be one of the best online stores. I've used a couple others, but they've been the best, and everyone I've talked to has had similar experiences. I'd avoid Marine Depot Live. I got the distinct impression dealing with them that it's just a business to them, and they don't care about the welfare of their livestock, just making a sale. Not to mention 2 of the 3 fish I ordered were wrong, and when they sent me a replacement for one of them, it was still wrong. A month later, the matter was finally resolved to no one's satisfaction.