The Mekong giant catfish, Pangasianodon gigas, is a very large, critically
endangered species of catfish in the shark catfish family, native to the
Mekong basin in Southeast Asia and adjacent China. In Thai folklore, this
fish is regarded with reverence, and special rituals are followed and
offerings are made before fishing it. Distribution and habitat
The Mekong giant catfish is a threatened species in the Mekong, and
conservationists have focused on it as a flagship species to promote conservation
on the river. Although research projects are currently ongoing, relatively little
is known about this species. Historically, the fish's natural range
reached from the lower Mekong in Vietnam all the way to the northern reaches of
the river in the Yunnan province of China, spanning almost the entire 4,800
km length of the river. Due to threats, this species no longer inhabits the
majority of its original habitat; it is now believed to only exist in small,
isolated populations in the middle Mekong region. Fish congregate during
the beginning of the rainy season and migrate upstream to spawn. They live
primarily in the main channel of the river, where the water depth is over 10
m, while researchers, fishermen and officials have found this species in the
Tonle Sap River and Lake in Cambodia, a UNESCO Biosphere Reserve. In the past,
fishermen have reported the fish in a number of the Mekong's tributaries;
today, however, essentially no sightings are reported outside of the main Mekong
river channel and the Tonle Sap region. Feeding
As fry, this species feeds on zooplankton in the river and is known to
be cannibalistic. After approximately one year, the fish becomes herbivorous,
feeding on filamentous algae, probably ingesting larvae and periphyton
accidentally. The fish likely obtains its food from algae growing on submerged
rocky surfaces, as it does not have any sort of dentition.
Appearance and size Grey to white in colour and lacking
stripes, the Mekong giant catfish is distinguished from other large catfish
species in this river by the near-total lack of barbels and the absence of
teeth. The Mekong giant catfish currently holds the Guinness Book of
World Records' position for the world's largest freshwater fish. Attaining an
unconfirmed length of 3 m, the Mekong giant catfish grows extremely quickly,
reaching a mass of 150 to 200 kg in six years. It can reportedly weigh up to 350
kg. The largest catch recorded in Thailand since record-keeping began in
1981 was a female measuring 2.7 m in length and weighing 293 kg. This
specimen, caught in 2005, is widely recognized as the largest freshwater
fish ever caught. Thai Fisheries officials stripped the fish of its eggs
as part of a breeding programme, intending then to release it, but the
fish died in captivity and was sold as food to local villagers.
Conservation Endemic to the lower half of the Mekong
River, this catfish is in danger of extinction due to overfishing, as well
as the decrease in water quality due to development and upstream damming. The
current IUCN Red List for fishes classes the species as Critically Endangered;
the number living in the wild is unknown, but catch data indicate the
population has fallen by 80% in the last 14 years. It is also listed in Appendix
I of CITES, banning international trade involving wild-caught specimens.
In The Anthropologists' Cookbook, Jessica Kuper noted the importance of
the pa beuk to the Lao people and remarked, "In times gone by, this huge
fish, which is found only in the Mekong, was fairly plentiful, but in the last
few years, the number taken annually has dwindled to forty, thirty or twenty, and
perhaps in 1976 even fewer. This is sad, as it is a noble fish and a mysterious
one, revered by the Lao." Fishing for the Mekong giant catfish is
illegal in the wild in Thailand, Laos and Cambodia, but the bans appear to be
ineffective and the fish continue to be caught in all three countries. However,
in recognition of the threat to the species, nearly 60 Thai fishermen agreed
to stop catching the endangered catfish in June 2006, to mark the 60th
anniversary of Bhumibol Adulyadej's ascension to the throne of Thailand.
Thailand is the only country to allow fishing for private stocks of Mekong
giant catfish. This helps save the species, as lakes purchase the small fry
from the government breeding programme, generating extra income that allows the
breeding program to function. Fishing lakes, such as Bueng Samran in Bangkok,
have the species up to 140 kg. The most common size landed is 18 kg, although
some companies specialise in landing the larger fish.
The species needs to reach 50–70 kg to breed, and it does not breed in lakes.
The Thailand Fishery Department has instituted a breeding programme to
restock the Mekong River. From 2000 to 2003, about 10,000 captive-bred
specimens were released by the Thai authorities. At present, specimens are
released into reservoirs rather than the Mekong River itself.
References External links
"Pangasianodon gigas". Integrated Taxonomic Information System.
Photo in National Geographic of a large specimen
Fresh Water Fish of Thailand