From 7.9 millimeters to 15 meters there is a lot of difference. Well, this is the one that exists between the smallest fish and the largest of all those that inhabit the planet. The smallest ever found, Paedocypris progenetica , has been discovered in a highly acidic swamp on the Indonesian island of Sumatra; the female measures 7.9 mm and the male, 10.3. Scientists say it is one of the rarest species in the world.
On the other hand, the whale shark, the largest of all , reaches up to 15 meters and 18 tons . However, Australian scientists who have been studying them for years have found that they are shrinking and that the average size has gone from seven meters to just five.
