Freshwater Fish Records
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. It was 9 feet long and weighed 646 pounds.
The fish in the photo
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
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 something 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.
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