The world’s smallest fish is Paedocypris progenetica, and was only recently discovered in the last decade. Scientists discovered it living in the forest swamps on the Indonesian island of Sumatra. Mature females measure just 7.9 millimeters — less than one third of an inch! In fact, until recently, Paedocypris was the world’s smallest known vertebrate animal, which has now been superseded by a minute frog (Paedophryne amauensis) from the New Guinean rain forests.
This tiny fish, a member of the carp family, has a partially see-through body and a reduced head skeleton, which leaves the brain completely unprotected by bone. This tiny, translucent fish has the appearance of larvae, possesses some bizarre grasping pelvic fins, and lives in dark tea-coloured waters with an acidity of pH3, which is more than 100 times more acidic than rainwater!
The Sumatran swamps were once thought to harbor very few animals, but research has revealed that they are highly diverse and home to many unique species that occur nowhere else. However, as with many such areas, this habitat is in much danger because the peat swamps have been damaged by large forest fires and they are still being threatened by industries such as logging and agriculture. As a result, several populations of Paedocypris have already been lost.
The previous record for smallest fish was held by an 8 mm species of Indo-Pacific goby. The United Kingdom’s smallest fish is the marine Guillet’s goby (Lebetus guilleti), reaching a whopping 24 millimeters in length!
Much needs to be done to save these magnificent tiny creatures to ensure their survival on this great planet.