Mekong giant catfish

Grey to white in color and lacking stripes, the Mekong giant catfish is distinguished from other large catfish species in the river by the near-total lack of barbels and the absence of teeth. Young Mekong catfish do exhibit barbels and oral teeth, but these features diminish as they age and are absent by the time they grow to be 30–50 cm in length. Mekong giant catfish are one of the largest species of freshwater fish. In 2005, the Mekong giant catfish attained the Guinness World Record for the world's largest freshwater fish. Attaining a length of up to , the Mekong giant catfish grows extremely quickly, reaching a mass of in only six years. Thai fisheries officials stripped the giant catfish, caught in 2005, of its eggs as part of a breeding program, intending then to release it, but the fish died in captivity and was sold as food to local villagers. ==Distribution and habitat==

lake 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 (above the tidally influenced brackish water of the river's delta) all the way to the northern reaches of the river in the Yunnan Province of China, spanning almost the entire 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. while researchers, fishermen and officials have found this species in the Tonlé Sap River and Lake in Cambodia, a UNESCO Biosphere Reserve. In the past, fishers have reported the fish in a number of the Mekong's tributaries. In December of 2024, 6 of the Mekong giant catfish were sighted and caught along the Tonle Sap River, in Cambodia. However, In 2005 the biggest Mekong giant catfish to be caught was in northern Thailand and weighed up to 292 kg. ==Ecology==

As fry, this species feeds on zooplankton in the river and is known to be cannibalistic. After about 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. Understanding of the species' migration pattern is incomplete. Spawning fish in the upper Cambodia are being over harvested. Fragmentation caused by infrastructure development of dams are becoming increasingly common posing threats to larval fish and reducing breeding abilities. Overfishing, damming, destruction of spawning and breeding grounds and siltation have taken a toll on the species' habitat. ==Relation to humans==

In Thai folklore, this fish is regarded with reverence, and special rituals are followed and offerings are made before fishing it. The species is represented as ancient art along the Mekong River. In 2000, fishermen hauled out 11 giant catfish. In 2001 they caught seven. In 2002 they caught just five. Mekong giant catfish along with the giant barb, giant pangasius, redtail catfish and alligator gar are a common sport fish in exotic fishing ponds in Thailand, Malaysia, and Vietnam. This is because of their giant size and because they often put up a strong fight after getting hooked. 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. A 2018 study suggests that the Mekong stocks could fall up to 40% as the result of dam projects. 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 commercial international trade involving wild-caught specimens. 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. 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 (บึงสำราญ) in Bangkok, have the species up to . The most common size landed is , although some companies specialise in landing the larger fish. The species needs to reach to breed, and it does not breed in lakes. The Thailand Fisheries 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. They are often hybridised with the iridescent shark to make the Mekong iridescent shark. A short body morph has been developed, similar to those of the paroon shark and iridescent shark. ==References==