Is it required to leave a conventional tip when the food service was not good?

My wife and I went to a fresh seafood restaurant and asked for a grilled fish. During eating it, I noticed that because of the stifness and dryness of the fish, that it had been previously cooked, and re-cooked when I asked for it. I should have asked to see the raw fish before placing the order. I told the waiter about it who told me that the fish was cooked from a raw one. But it I know about this matter since I like seafood and have had it many times before. When the check came in, I left no tip, and my wife keep telling me that I should have left the conventional tip anyway. Any comments?