Miniature Asian fish sets a whale of a record
PARIS (AFP) - Scientists from Europe and Singapore say they have discovered
the world's tiniest fish -- a species that lives in peat wetlands in
Southeast Asia and, when fully grown, is the size of a large mosquito.
The record-busting newcomer to the biodiversity book, Paedocypris
progenetica, is a distant cousin of the carp, say the discoverers, who
publish their findings on Wednesday in Proceedings of the Royal Society B, a
British journal.
Skinny and transparent, 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.
These so-called "blackwater" swamps are a unique landscape of flooded trees
growing in water-logged, soft peaty soil that is often several meters (10
feet) thick.
The water is stained reddish-black, like very dark tea, appearing black-in-
the surface. It is extraordinarily acidic, having a pH3 value of only three,
the same as a sour apple.
The scientists needed a special stereoscopic microscope to accurately
measure the fish.
The smallest adult specimen they netted was a mature Paedocypris progenetica
female, found in Sumatra, that came to just 7.9mm (0.31 of an inch) from
nose to tail, making it not only the world's smallest fish but the smallest
vertebrate too.
She nudged out the previous record holder, a marine fish of the Western
Pacific called the dwarf goby (Trimmatom nanus), which comes in-in-8mm (0.32
of an inch)-in-sexual maturity.
The team also found a related Paedocypris species, P. micromegethes, in
Sarawak in Malaysian Borneo.
At 8.8mm (0.35 of an inch), P. micromegethes is the second smallest
freshwater vertebrate ever found.
The fish was discovered by Maurice Kottelat and Tan Heok Hui, who are
researchers-in-the Raffles Museum of Biodiversity Research-in-the National
University of Singapore.
They were assisted by Ralf Britz of Britain's National Museum of Natural
History and Kai-Erik Witte-in-the Max Planck Institute for Developmental
Biology in Tuebingen, Germany.
Kottelat said P. progenetica has "a very rudimentary skull" which leaves the
brain exposed.
Evolutionary pressures have caused the fish to develop highly modified fins
to survive in its special environment. Males also have a tough pad on the
front of the pelvic girdle that may be used to help them clutch onto females
during mating.
"The discovery of such a tiny and bizarre fish highlights how little we know
about the diversity of Southeast Asia," said Kottelat.
"This is all the more serious because the habitat of this fish is
disappearing very fast, and the fate of the species is now in doubt."
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