It depends on what you mean by fully cooked and what kind on fish it is. Parasites in fresh water fish can make a person sick if the fish does not get hot enough to kill them. Parasites in salt water fish cannot live in the human body.
What Happens If You Eat Fish Not Fully Cooked?
You are at a sushi bar
I don't want to die I just need food poisening :S
Many people eat raw fish - ceviche, sushi, etc. You wil be fine - you have now entered the era of fine dining to many people.