The smallest fish on record is no longer the 8mm Indo-Paciffic gobby, but rather a 7.9mm member of the carp family known as Paedocypris progenetica. Discovered in a peat bog on Sumatra island by Switzerland’s Maurice Kottelat and Singapore’s Tan Heok Hui, this fish is remarkable not only because it is so small, but because of the way it has adapted to thrive in its environment.
First, the fish lives in murky peat bog water with a ph of 3. This is about 100 times more acidic than rainwater, so it is amazing to find a fish that is actually able to live in it.
Secondly, it has “bizarre grasping fins” with exceptionally large muscles. The purpose of these is unclear at the moment, but it is theorized that fish uses them to grasp its mate during copulation.
Finally and most importantly according to Kottelat, is the scientific significance of finding a complete vertebrae in such a tiny body. Apparently this is nearly unheard of in organisms this small.
It will be interesting to learn more about this amazing little fish as more research is conducted. The Natural History Museum reports that several populations of Paedocypris have already been lost due to habitat destruction caused by rampant development and intensive farming, so researchers are trying to learn all they can about this amazing specimen before it too becomes extinct.