Scientists have discovered the world’s smallest fish on record in an
acidic peat swamp in Indonesia, with a see-through body and a head
that is unprotected by a skeleton, researchers said Wednesday.

Mature females of the Paedocypris progenetica, a member of the carp
family, only grow to 7.9 millimeters (0.31 inches) and the males have
enlarged pelvic fins and exceptionally large muscles that may be used
to grasp the females during copulation, researchers wrote in the
Proceedings of the Royal Society, published Wednesday by the Royal
Society in London. Amazing news.

Paedocypris progenetica, the world's smallest fish on record

“This is one of the strangest fish that I’ve seen in my whole career,’
said Ralf Britz, zoologist at the Natural History Museum in London,
who helped analyze the fish’s skeleton. “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.”

http://e-fishingnews.com/amazing/594