Paedocypris progenetica. Photographed in aquarium with a milimetric scale to show the diminutive size of the fish. It's a fish endemic to the Indonesian islands of Sumatra and Bintan where it is found in peat swamps and blackwater streams. It is the smallest known fish in the world, with females reaching a maximum standard length of 10.3 mm and males 9.8 mm. A female measuring only 7.9 mm was the smallest known mature specimen. It held the record for the smallest known vertebrate until the frog Paedophryne amauensis was formally described in January 2012. The 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 at least 100 times more acidic than rainwater. Those 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. France