Raw fish for the masses!
Eating raw fish may sound disgusting at first, but until you've tried it you should not hold an objectionable opinion about it. It is interesting to say that people have eaten raw fish for a very long time, and probably even our first human ancestors did it. After all, the discovery of fish came before the discovery of fire-making, right? There is ample evidence that early humans ate almost everything raw, including meat. But that's another story. Anyway, what raw fish offers is the very tender texture as compared to raw meat. It is also flavorful since it already contains flavor molecules like IMP or glycine and glutamic acid. In other words, no need for browning there, although it does of course add some new flavor to the fish (partly on the cost of losing some of the inherent flavors). On the other hand, cooking will destroy some of the prime fresh feeling, which is the very thing that "raw eaters" enjoy. The natural flavor and texture of a raw fish can be further modified by milder treatments, like salting or acidifying. In short, you save yourself the fuss of heating, and you will enjoy something new on your table, unless you haven't eaten raw fish before.
The most known and popular forms of raw fish have to be SUSHI and SASHIMI. Originating in Japan, they quickly became internationally famous for their special taste. Sushi means "salted" and is actually applied to the rice and not the fish, although it can certainly be cured with salt and/or acid as well. The important thing when making sushi is to take a very good care about the hygiene. Since the fish is raw, sushi chefs use chlorinated water (anti-bacterial) and frequent change of cookware and even clothes to minimize the bacterial growth and contamination.
Another form of salted raw fish is POKE and LOMI, originating in Hawaii. The difference between these two is not very big. Lomi is prepared by squeezing the fish pieces between the fingers, to make it even more tender. Both poke and lomi are then embedded in salt and left to cure for a certain period of time, until enough water has been drawn out of the fish and it has become firmer. The usual fish used for poke or lomi include tuna and marlin.
Raw fish can also be treated by acidic liquids, like lemon juice or juice from some other citrus fruits. This is the idea behind CEVICHE - a South American dish. The curing liquid, besides its acidic component, also contains some aromatic and seasoning ingredients, like onion or chili. The point behind using acids is to denature the proteins in the fish, which is the same phenomenon happening when cooking, although the denaturation is more gentle and the change of opacity of the fish meat is not that pronounced as when you cook the fish.
One very important thing to keep in mind when working with raw fish is the danger of bacterial growth and contamination. The sushi chef's routines have already been mentioned. But the very first step in getting an unblemished raw fish is to obtain a really fresh specimen that haven't been handled by humans and time for a very long time. Some fish may also contain worms, which are normally killed by cooking, but it is naturally not applicable here. However, the fish may be frozen for about a week at -20C/-4F - this is recommended to kill any possible parasites in the fish.