TOKYO (Reuters) - As Japanese sushi conquers restaurants and homes around the world, industry experts are fighting the side-effects of the raw fish boom: fake sushi bars, over-confident amateurs, poisoned consumers. Once a rare and exotic treat, seaweed rolls and bites of raw tuna on vinegared rice are now familiar to most food fans. So familiar, in fact, that many hobby cooks in Europe and the United States like to make them in their own kitchens.