There are fish that exist at the edge of what seems plausible. The giant freshwater stingray — pla kaben yak (ปลากระเบนยักษ์) — is one of them. Not because of spectacular coloration or dramatic surface behavior, but because of its scale: a species that, at maximum development, produces animals weighing several hundred kilograms, broader across the disc than most people are tall, carrying a venomous barb behind them on a whip-like tail that can exceed two meters in length. In a river. In the middle of mainland Southeast Asia. This is not a creature of the deep ocean or the Amazonian blackwater — it lives in the Chao Phraya and Mae Klong river systems, sometimes within fifty kilometers of downtown Bangkok, in the same water that local fishermen have worked for generations.
The giant freshwater stingray (Urogymnus polylepis, formerly classified as Himantura chaophraya) is also critically endangered. Every angler who pursues this fish should hold both facts simultaneously: it is among the most extraordinary sporting encounters available anywhere in freshwater fishing, and it is a species in serious trouble. Fishing for it without absolute commitment to catch-and-release is not a grey area.
Identification and Biology
Urogymnus polylepis belongs to the family Urogymnostidae (sometimes placed within the broader Dasyatidae) and is the largest known freshwater fish species by disc width, and potentially one of the heaviest freshwater fish on Earth by mass — rivaling the giant Mekong catfish and arapaima at exceptional sizes. The disc — the flattened, wing-like body extension that gives rays their characteristic form — is roughly circular to slightly wider than long, with a smooth upper surface in pale greyish-brown or tan, shading to white on the underside. There are no distinctive markings on adults; the species is identifiable by its size, disc shape, and the characteristic smooth, scaleless skin.
The tail is exceptionally long — typically one-and-a-half to two times the disc width — and armed with one or more serrated venomous barbs midway along its length. These barbs are a serious defensive weapon and the primary safety concern when handling these fish. They are not used to attack but will be deployed if the fish feels threatened or pinned.
Giant freshwater stingrays feed on the bottom, consuming mollusks, crustaceans, worms, and fish using a crushing jaw structure adapted for hard-shelled prey. They are almost entirely benthic, spending most of their time resting or hunting along river and estuarine floors. Movement between habitats is tied to seasonal water level changes — fish move into flooded areas during high water and concentrate in deeper channels during the dry season.
The species is ovoviviparous — embryos develop internally and are born live, in litters of one to three pups. Reproduction is slow, gestation periods are long, and sexual maturity is reached relatively late, making population recovery from depletion extremely slow. Lifespan in natural conditions is not fully established but is believed to be several decades for large specimens.
The taxonomic reclassification from Himantura chaophraya to Urogymnus polylepis reflects recent molecular and morphological work that revealed the Thai river population to be distinct from what had been a loosely assembled species grouping. The current understanding is that U. polylepis is endemic to large river systems in mainland Southeast Asia, with the Chao Phraya and Mae Klong systems being its core habitat in Thailand.
Where to Fish for Giant Freshwater Stingray in Thailand
The practical reality of fishing for this species is that it is a guided, specialist endeavor. You cannot simply turn up at a riverbank with heavy tackle and expect to connect with a fish — the knowledge, equipment, and landing logistics involved are entirely beyond casual DIY fishing.
The Mae Klong River and its associated waterways in Samut Songkhram and Ratchaburi provinces are the primary location for guided stingray fishing in Thailand. A small number of specialist guides operate here, working the deep river channels from purpose-built boats equipped with appropriate tackle and, critically, the infrastructure to handle, document, and release very large animals safely.
The Chao Phraya river system also holds population remnants, and historically the species was documented in the Bang Pakong river as well. Access to these populations for sport fishing is less structured, and encounters are more opportunistic.
Book Specialist Guides Only
Do not attempt to fish for giant freshwater stingrays independently. The logistics of safely handling an animal that may weigh 100–300 kg in moving water, managing a venomous tail barb, and executing a proper catch-and-release require experienced guides and appropriate equipment. An improperly handled release is dangerous to both the angler and the fish.
Internationally, the species has attracted significant research attention. Teams from Mahidol University and overseas conservation organisations have worked with local guides to tag and monitor individual fish, building population data on a species that is poorly understood relative to its ecological status. Some guided fishing trips are conducted in formal partnership with research programs, meaning your catch may contribute directly to knowledge about this animal. This is worth knowing when you book.
Season and Conditions
The dry season — roughly November through May — produces the most consistent results. During this period, river levels drop and the fish concentrate in defined deep-water channels rather than dispersed across flooded terrain. Water, while never particularly clear in large lowland rivers, is somewhat less turbid than during the monsoon months. Fish are locatable by experienced guides who understand the seasonal holding patterns.
The wet season dispersal is not simply a logistical inconvenience — fish genuinely become much harder to find when river levels rise and habitat complexity increases. Some guides suspend operations during peak monsoon months, roughly July through September, though the precise timing varies by year and by river condition.
Water temperature in central Thailand's lowland rivers stays relatively stable — typically between 26°C and 32°C throughout the year — and is not a significant factor in the fish's seasonal behavior compared to water level and turbidity.
Technique and Rigging
Bait fishing from an anchored or semi-anchored boat in deep river channels is the standard approach. The fish are located through experience and pattern — guides who have worked these rivers for years know the holding pools, the seasonal channel shifts, the tidal influence in lower reaches. There is no shortcut to this local knowledge.
Baits are typically fresh fish — large whole fish or substantial cut sections — presented on the bottom using running ledger rigs heavy enough to hold position in river current. Weight requirements in the Mae Klong can be substantial — several hundred grams of lead in faster current. The leader material must balance strength with a degree of flexibility given the extraordinary stress of landing a large stingray: heavy-duty monofilament or fluorocarbon in breaking strains well above 100 lb is typical.
Hook selection is critical for a species that must be released with minimal damage. Circle hooks are strongly preferred — they are far less likely to be deeply embedded, reducing injury at hook removal. Hooks must be strong enough not to bend or fail during a fight that may last an hour or more on a large fish, but they must also be removable without extensive equipment.
The strike on bottom-fished bait can be subtle — a large stingray covering a bait with its disc may not produce an obvious rod tip movement. Experienced guides watch for slight line movements and changes in rod tip behavior that indicate a fish is present.
Tackle Setup
This is specialist heavy-duty work. Rod and reel combinations for giant stingray fishing are in an entirely different category from most freshwater fishing.
Rods in the eighty-to-one-hundred-plus pound class, typically roller-guided boat rods, are standard. Reels are large-capacity conventional (baitcast-style) units with smooth, powerful drags capable of handling sustained runs from extremely large fish. Line is typically heavy braid — sixty to one hundred pound — on substantial spools. The complete outfit resembles offshore trolling gear more than conventional freshwater tackle, and this is not coincidental: the stresses involved are genuinely comparable.
Landing a giant stingray requires a team. Multiple guides are typically present for large fish, and purpose-built slings or shallow beaching areas are used to bring the fish to a position where measurements and photographs can be taken before a controlled, assisted release back into the current. No gaffing, no gill-grabbing, no suspension of the fish vertically. The tail barb must be kept track of at all times — guides position themselves carefully relative to it throughout the process.
Records and Notable Catches
The giant freshwater stingray has produced some of the most significant freshwater catches documented anywhere in the world. Disc widths exceeding two meters and weight estimates above 300 kg have been recorded for exceptional specimens from the Mae Klong system. Weighing these animals precisely is essentially impossible in a catch-and-release context — estimates from disc width measurements and weight formulae are the standard documentation method.
International media attention has periodically focused on the species when particularly large specimens have been landed and released. Several such events have been documented in collaboration with Mahidol University's freshwater research program, which has been running intermittently for years. These documented catches represent some of the largest freshwater fish caught on rod and reel anywhere on Earth.
Separately, in 2022, a giant freshwater stingray caught in Cambodia's Mekong River was weighed at approximately 300 kg (661 lb) — at the time reported as potentially the largest freshwater fish documented on record. This Cambodian population is considered part of the same species complex.
The lack of formal IGFA record pursuit is deliberate and correct. The fishing community that targets this species has, by consensus, declined to pursue formal records in the recognition that weighing these fish properly would require treatment incompatible with their survival and welfare.
Conservation and Ethics
The giant freshwater stingray is classified as Critically Endangered on the IUCN Red List — the highest category short of extinction. Population decline has been driven by a combination of factors: habitat degradation through river dredging and dam construction; incidental bycatch in commercial fishing gear, particularly in gill nets where entanglement causes drowning; targeted harvest for food markets; and the extremely slow reproductive rate that prevents rapid recovery even if pressures ease.
The species' large size means that river engineering — sand dredging, navigation modifications — directly impacts its foraging and breeding habitat. Dam construction on tributaries disrupts seasonal movement patterns. The urbanization of the Chao Phraya floodplain has eliminated historical habitat that once supported larger populations.
This conservation context makes the ethics of sport fishing for this species unusually clear-cut. Catch-and-release is not a preference — it is the only responsible framework. Any harvest of giant freshwater stingray, anywhere in Thailand, is deeply incompatible with the species' survival. Beyond individual conduct, anglers who fish for this species bear some responsibility for advocacy: supporting the research programs that work on the fish, choosing guides who operate with proper care protocols, and being candid about the species' status when discussing it with others.
To catch a giant freshwater stingray is to hold, briefly, something the world may soon lose. That weight is not only in the fish.
The most significant practical contribution sport anglers can make — beyond individual C&R — is financial support for research and habitat protection through the organizations working on the Chao Phraya and Mae Klong systems. Some specialist guides donate portions of their fees to these programs, and selecting such operations is a meaningful choice.
What It's Like to Hook One
The fight begins, often, in ambiguity. A large stingray covering a bait with its disc may not register on the rod tip in any dramatic way. The guide sees something, recommends you pick up and apply pressure, and what you find at the other end of the line — rather than the nothing you feared — is the sensation of applying force to something that has no immediate interest in moving. Not a snag. Something that breathes, that shifts slightly, that eventually decides to move.
And then it does. A large stingray powering away from an anchored boat along the bottom of a river channel creates a pressure on tackle that is unlike most freshwater experiences. There are no jumps, no surface runs. There is instead a remorseless, grinding, horizontal power that transmits through heavy braid and stiff roller rod as a continuous, almost geological force. The fish does not panic. It simply moves, and your equipment must hold, and you must hold it.
The fight on a very large fish can last well over an hour. The physical demand on the angler is real — bracing against a heavy-duty outfit while a several-hundred-kilogram animal exerts sustained force is exhausting in a way that has nothing to do with technique. When the fish finally tires and the guide begins the process of bringing it alongside — the enormous flat disc pale and enormous just below the surface, the vast tail curling in the current — the overriding emotion is not triumph but something quieter. You are looking at an animal that may be thirty years old, that has navigated the same river bends through monsoons and droughts, that carries a design three hundred million years in the making. The fact that you are here, that this fish still exists in this river, is remarkable. The fact that its future is genuinely uncertain makes the moment heavier than any fish you've caught before.
Plan Your Trip
The Bangkok region guide covers the Central Plains in detail and includes current information on access to Mae Klong and Chao Phraya river fishing. The catch-and-release rules and ethics guide is required reading before any stingray trip. For context on the other extraordinary large-fish targets available in Thai rivers, see our profiles of giant Mekong catfish and Chao Phraya catfish.
