Walk through the gate at IT Lake Monsters or Gillhams Fishing Resort and you are looking at something that has no equivalent anywhere outside South America — arapaima and Amazon redtail catfish sharing the same lake, available to anyone with the right tackle and a day to spend. Both species have been transplanted from their native Amazonian rivers and are now among the most sought-after quarry in Asian freshwater fishing. But they are radically different fish to target, and choosing between them is not as simple as picking the bigger one.
The Case for Arapaima
Arapaima gigas is the argument for pay lakes that even sceptics find difficult to dismiss. These are the largest scaled freshwater fish on earth, and the specimens at venues like IT Lake Monsters and Gillhams regularly exceed 100 kilograms. The world record stands above 200kg, and Thailand is one of the few places outside the Amazon where fish approaching that weight can be targeted.
What makes arapaima uniquely compelling is that they are obligate air breathers. They must surface to gulp air every 10–15 minutes, which means when a big arapaima rolls beside you — fin breaking the surface, armoured scales catching the light — you are witnessing the fish's physiology in real time. When one is hooked and erupts into the air, it is not a trout leap. It is a prehistoric creature the length of a surfboard clearing the water. That moment is why anglers travel from Europe, America, and Australia specifically to fish for this species.
When a hooked arapaima erupts into the air, it is not a trout leap. It is a prehistoric creature the length of a surfboard clearing the water.
The fight itself demands respect. Keeping tension on an airbreeding fish that can use its jumps to throw a hook requires both skill and composure. Dipping the rod tip when it leaps, keeping the line tight through the run — these are genuine technical demands. For more on preparing your gear, see our arapaima tackle guide.
The Case for Amazon Redtail Catfish
The Amazon redtail catfish — Phractocephalus hemioliopterus — is a more demanding fish to catch, and that's not nothing. Its vivid colouration (deep charcoal body, white belly, flame-orange tail) makes it one of the most visually striking freshwater fish in the world. It is also, pound for pound, one of the more grudging fish to bring to the surface once hooked.
Redtail catfish at Thai venues are often found holding over deep structure — channels, submerged timber, and drop-offs. If you're getting bites near the margins but failing to connect, move your rig 5–10 metres further into the swim and fish heavier.
Triggering a bite in the first place is the real challenge. Redtails at established venues have been caught and released many times and can be extremely cautious around rigs. Presentation matters — fresh, oily bait fished tight to the bottom on a correctly sized hook outperforms any shortcut. When the rod finally goes around, the fight is a prolonged bottom-hugging battle with no respite. There are no theatrics, just relentless power.
Comparing the Venues
Both species are available at the same top-tier venues — IT Lake Monsters and Gillhams are the two headline destinations — but with different emphases. IT Lake Monsters holds some of the largest arapaima in Thailand and attracts serious record-chasers. Gillhams offers a more resort-style setting in Krabi that combines species access with accommodation quality.
For the redtail specifically, Boon Mar Ponds and Pilot 111 also carry good populations. Boon Mar in particular is known for producing very large specimens in a setting that allows careful bottom-bait presentation without the time pressure of a packed commercial venue. Compare the two main venues head-to-head in our IT Lake Monsters vs Pilot 111 article.
Tactics Side by Side
For arapaima, the most productive approach at most Thai venues is large deadbait or livebait fished under a surface float, allowing the bait to sit in the arapaima's natural strike zone. High-visibility hooklinks help you spot the moment the bait is taken before a full run develops. On venues that permit it, a large surface lure — popper or stickbait fished slow and deliberate — produces strikes that defy description.
For redtail, fish the bottom. Cut fish, chicken liver, or high-oil pellets moulded around a hair rig produce the most consistent results. Add a small PVA bag of crushed pellets around the hookbait to build a localised smell trail without spooking the fish with a large free-bait spread. Use fluorocarbon leader of at least 60lb — redtail have rough mouths and will abrade mono.
Who Should Target Which
Target arapaima if: you want the single most dramatic freshwater fishing experience available in Thailand, you're fishing with someone who needs immediate visual excitement (the rolling and surfacing happens even before you're hooked up), or you specifically want to say you've caught one of the world's largest freshwater fish.
Target redtail catfish if: you're a technical angler who finds the bite presentation challenge as satisfying as the fight, you want a fish that will work you hard without the luck element of an aerial jump throwing the hook, or you have limited upper-body strength and want a hard fight that stays underwater.
The ideal session: fish the first half of the day targeting arapaima when they're most active and rolling visibly, then switch to a bottom-bait redtail approach for the afternoon when the surface activity drops off.
Verdict
Arapaima is the headline act, and rightly so. No other freshwater fish in the world combines raw size, prehistoric spectacle, and aerial drama in the same package. If you're visiting Thailand's top venues for the first time, target arapaima. The experience is genuinely unrepeatable.
But do not underestimate the redtail catfish. Its combination of challenging bite, deep grinding fight, and stunning colouration makes it one of the most satisfying freshwater species you can target anywhere in Asia. For the angler who wants craft over spectacle, the redtail frequently wins the argument.
See also: Bangkok Pay Lakes vs Wild Fishing | Arapaima vs Mekong Catfish: Which Fights Harder?
