Funny story. I was in Eugene OR on a business trip and grabbing dinner at the Fisherman's Market. As I was waiting to order, I overheard an employee taking a call from a customer asking if they had walleye. The employee said something like, "Walleye? I've never even heard of that. What is it?" I helped the poor guy out and said it's a lake fish from the midwest, so you wouldn't have it here.

On topic, I find tilapia to be either bland or muddy. It seems that sometimes, certain chemicals build up in farm-raised fish due to the presence of cyanobacteria. Since cyanobacteria blooms come and go, you might have a "muddy" fish or a cleaner tasting fish. That said, I think the texture is fine - just not a fan of the flavor. Would much rather be eating Patagonian toothfish, although tough to find sustainably caught.