Folks, I generally eat only fish that I catch. So, there is no doubting the freshness. (And I have Atlantic cod in the fridge that I caught yesterday). My one bit of advice. Learn how to clean/fillet a whole fish. That way, you can be sure that the fish is fresh. When in the store, 1) look into the fishes eyes. If cloudy...run away. 2) examine the gills. If they are not brightly colored, the fish has been frozen. 3) hold it up to your nose and take a whiff. If it smells fishy, it has been sitting around for a few days.
As for tilapia, no way!