GUANT CATFISH ALERT

According to National Geographic: Fishermen in northern Thailand netted a huge catfish in the Mekong River on May 1. Nearly nine feet long (2.7 meters) and as big as a grizzly bear, the behemoth tipped the scales at 646 pounds (293 kilograms). Experts say the fish, which belongs to the species known as the Mekong giant catfish, may be the largest freshwater fish ever recorded. See the extraordinary pictures here:

See also:
Men catch 300kg monster catfish
June 30, 2005
Story claims that the fish has been confirmed as world's largest, 11 pounds heavier than the previous record holder - another Mekong catfish. The Mekong is a good habitat for such monsters because it is one of the deepest rivers in the world, reaching depths of more than 200 feet. The Mekong giant catfish is southeast Asia's largest and rarest fish

The Imperiled Giants of the Mekong
[American Scientist. May/June 2004]
Ecologists struggle to understand—and protect—Southeast Asia's large migratory catfish
Zeb S. Hogan, Peter B. Moyle, Bernie May, M. Jake Vander Zanden, Ian G. Baird
Southeast Asia’s Mekong river supports a vast freshwater fishery. One of the species caught by local fishers is the Mekong giant catfish (Pangasianodon gigas), which according to 'The Guinness Book of World Records' is the planet’s largest freshwater fish. But fewer and fewer examples of this huge fish have turned up in nets recently, and last year the World Conservation Union added this catfish to its list of critically endangered species. Although the loss of this charismatic fish would be a tragedy in itself, the plight of the Mekong giant catfish also highlights the precarious position of other Pangasiid catfish species inhabiting the Mekong river. Hogan and his colleagues explain their efforts to understand the migratory behavior of these fish in hopes of improving the chances for their long-term conservation.

In answer to a reader's letter in the following issue, Dr Hogan wrote:

Surprisingly, it is not 100 percent clear which species of freshwater fish is the largest. This uncertainty arises in part from our lack of detailed knowledge of the diversity of freshwater fish. (Many poorly studied fish live in exceptionally large, deep or remotely located water bodies.)

We also need a clear definition of just what is a large freshwater fish. For our purposes, we defined "largest freshwater fish" as the largest fish in terms of biomass that spends its entire life cycle in fresh water and for which there are reliable records.

The largest fish found in fresh water are indeed the sturgeons, but they obtain a majority of their growth in marine and estuarine environments, migrating into fresh water mainly to spawn. Even the hold that the Mekong giant catfish has on the largest–freshwater–fish title is tenuous, because weights of large fish are prone to exaggeration and error.

Here are some other contenders for the title, with alleged top weights: the Mekong giant carp (300 kilograms), the Mekong giant stingray (500 kilograms), the arapaima and goliath catfishes of the Amazon (300 kilograms), the Gnooch of South Asia (300 kilograms) and the Wels catfish of Europe (once 5 meters and 300 kilograms, now smaller).

Almost all of these species are now rare, so it is difficult to determine their maximum size. I am currently trying to determine which species is in fact the biggest, and I suspect the giant catfish will still come out as one of the top three! Interestingly, in terms of biomass and length, the largest freshwater fish may be the giant stingray of the Mekong, which may attain a weight of over 500 kilograms and measure more than 5 meters from snout to tip of tail.

Mass of catfish info at Conservation.mongobay.com

See IUCN: 'Giant Catfish on Brink of Extinction'