Freshwater
Fish Records
It's official!
The new world record holder for the biggest freshwater fish is the Giant
Mekong catfish (Pangasius gigas).
The biggest one ever captured and measured was caught in Thailand in
May of 2005.
The fish in the photo below was captured
by some fisherman where the species is considered endangered, but can
still be caught with special permits. The fish was turned in to the
Department of Fisheries where the eggs and sperm are collected from
these rare giants and harvested for a captive breeding program to keep
the species alive.

This giant catfish caught in May of 2005 was 9 feet long and weighed
646 lbs. This is more than 5 times bigger than the 'world record'
catfish caught in North America. |
This giant catfish inhabits the waters
of the Mekong River in China, which flows southward into Southeast Asia.
This fish is found as far south as Cambodia and Thailand where it is
known as Pla Buk, which means simply "huge fish".The dimensions
of these catfish are very impressive, with the largest supposedly growing
up to 10ft/3m and weighing up to 660lbs/300kg.
Scientists have recently discovered
someting amazing about the Giant Mekong catfish; they live out part
of their lives at sea. Most people have the impression of catfish as
slow, lumbering bottom-feeders, but it turns out that the migration
routes of these catfish rival those of the better known salmon. Scientists
have recorded Pangasius gigas traveling as much as 600 miles
(1000 km) inland from the south China sea up the Mekong River to spawn.
The waters of the Mekong River are
very murky and make it difficult to track the movements of the fish.
In order to determine where the Mekong catfish have been, scientists
examined chemical markers called isotopes
in bone and muscle tissue of catfish from the Khone Falls region of
the Mekong. The team found evidence that the freshwater-dwelling fish
had migrated recently from a marine habitat. Although this method of
fish tracking is a highly regarded method, it appears that this is the
first time it has been used to track the migration routes of river catfish
species from a marine environment.
The recent discovery that Mekong catfish
are anadromous, (moving from coastal waters
into fresh waters to spawn) has surprised even scientist's long-held
notions of freshwater species. It may be that many other species of
catfish also have similar migration habits, and that other species of
freshwater fish may be found living part of their lives at sea. It certainly
gives new meaning to the concept of "freshwater fish", if
they spend part of their lives living in the salty waters of a marine
environment.
As big as the Giant Mekong catfish
can get, there are rumored to be other species of freshwater fish whose
dimensions rival those of the Mekong catfish. Among them are the Arapaima
and huge freshwater stingrays, both found living in the Amazon
River. The giant Chinese paddlefish is also a serious contender
for world's biggest freshwater fish, but very little is known about
this species that seems to be rapidly disappearing.
For more information about giant freshwater
fish species see the National Geographic sponsored Megafishes
Project, and meet the scientists
who travels the world looking for the world's biggest freshwater
fish.