Smallest known fish found in Indonesia

BANGKOK, Thailand — Scientists say they have discovered the world's smallest known fish in threatened swampland in Indonesia.

The fish, a member of the carp family, has a translucent body and a head unprotected by a skeleton.

Mature females grow to less than a third of an inch long. The males have enlarged pelvic fins and muscles that may be used in reproduction, researchers wrote in a report published Wednesday by the Royal Society in London.

"This is one of the strangest fish that I've seen in my whole career,' said Ralf Britz, a zoologist at the Natural History Museum in London. "It's tiny, it lives in acid and it has these bizarre grasping fins. I hope we'll have time to find out more about them before their habitat disappears completely."

The fish are found in an acidic peat swamp on the island of Sumatra. Indonesian peat swamps are under threat from fires lit by plantation owners and farmers as well as unchecked development and farming. Researchers say several populations of the tiny fish, Paedocypris progenetica, already have been lost, according to the Natural History Museum.

The previous record for world's smallest fish, according to the Natural History Museum, was held by a species of Indo-Pacific goby one-tenth of a millimeter longer.

"You don't wake up in the morning and think, 'Today we will find the smallest fish in the world,' " fish expert Maurice Kottelat, who helped discover the fish, said in a telephone interview from his home in Switzerland.

According to researchers, the little fish live in dark water at least 100 times more acidic than rainwater. Such swamps were once thought to harbor few animals, but recent research has revealed that they are highly diverse and home to many unique species.