Another Reason To Filter Water?

Forget copepods. There are carp in the water. At least in Southeast Asia. Tiny fish, distant relatives of carp, transparent and skinny. They found a mature female just 7.9 millimeters long. Of course, they might just be kosher - they are relatives of carp and have (some sort of) fins, after all. Don't know about scales.

AP's article.

News in Science coverage:

The record-busting newcomer, Paedocypris progenetica, is skinny and transparent, and a distant cousin of the carp, the researchers say.

The elusive fish lives in highly acid peat swamps on the Indonesian island of Sumatra and in the Malaysian part of Borneo that are threatened by forestry and agriculture.

The scientists needed a special stereoscopic microscope to accurately measure the fish.

The smallest adult specimen they netted was a mature female, found in Sumatra, that came to just 7.9 millimetres from nose to tail.

This makes her not only the world's smallest fish but also the world's smallest vertebrate.

...

Both articles have nice photos.
And an article in New Scientist:
The male fish also has an interesting feature, according to New Scientist:

Projecting downward from about midway along the underside of the male's body, the fin has unique anatomical features which probably help it grip females during mating. Just in front of the fin is a large group of muscles that form a kind of "gripper" ...