Mercury in fish has developed into a problem in that it has caused problems for young children. The mercury in fish has caused some childrens IQ's to drop and also has contributed to blindness. In an ideal world, mercury wouldn't be a problem, but it is a problem because it is being polluted into the water and habitats around the world.
With a label on each package indicating how much mercury is in the fish when purchasing it, people will know whether it is safe to eat. We can reduce the problems that mercury is causing to young children with a label put on each individual piece of fish sold. So please require labels put on all fish sold indicating the mercury levels in that piece of fish!