I'm not sure why this still amazes me, but with all of the media blather that gets generated on food safety, nobody comes close to getting it right.
The issue to be concerned about is bacterial contamination. This goes double for anything eaten raw, and is of extreme concern for any meat products eaten raw. Personally, I think that eating any meat product raw is just foolish.
A couple of generations ago, bacterial food poisoning was the third-leading cause of death in the U.S., and it still ranks high in much of the world. Now we have a rigorous system of inspection and distribution of food that minimizes contamination, but it can never eliminate it entirely. The consumer still has to exercise a little responsibility and care.
You cannot tell whether food is contaminated or not merely from its appearance, taste, or odor.
BTW, raw fish should definitely be considered off-limits to anyone with a weakened immune system.
For fish, the next most important concerns are toxins that accumulate in the tissues, but originate from other organisms that the fish eat. This is more common in reef fish and shellfish, but is always present to some extent. These toxins come from protozoa and algae, and they may not be entirely inactivated by cooking. For tropical fish, the most well-known of these toxins is ciguatera.
The next concern is scombroid poisoning. This comes from histamines that are produced in fish tissues after they die. The rate at which these molecules accumulate is slowed by refrigeration, but they will always accumulate to some extent, until the fish is cooked. The symptoms are basically an allergic reaction. Fish of the tuna family are particularly likely to cause scombroid reactions if not handled carefully at all times.