Nope, villman was right. I was listening to the reporters, and stingrays are one of the more benign sea creatures. There are only a few thousand incidents of stingray attacks in a year, and they are hardly deadly unless someone is highly allergic to the venom. It's similar to a large bee sting.
It's just that in this case, the barb got him right in the chest and pierced his heart. For one thing, it had to be a huge stingray to do that.