Fish of Thailand: Reef, River and Open Water

Humphead Wrasse (Napoleon Wrasse) Rare Endangered

Cheilinus undulatus

A giant, curious reef fish with thick lips and a bulging forehead, able to crunch prey that few other animals can eat.

Where: Similan, Hin Daeng and Hin Muang, outer reefs. Best: Dive season, Nov-Apr.

Bumphead Parrotfish Occasional Vulnerable

Bolbometopon muricatum

A hulking, bull-headed parrotfish that rams and bites living coral, turning reef rock into the white sand of tropical beaches.

Where: Similan and outer Andaman reefs. Best: Dive season, Nov-Apr.

Leopard Coralgrouper Regular

Plectropomus leopardus

A blue-spotted red grouper that hunts in partnership with moray eels and octopus.

Where: Reefs across the Andaman. Best: Nov-Apr.

Clown Triggerfish Rare

Balistoides conspicillum

Perhaps the most flamboyant fish on the reef, a black triggerfish spotted with huge white polka-dots and a saddle of gold.

Where: Hin Daeng and Hin Muang, Similan deeper reefs and walls. Best: Dive season, Nov-Apr.

Mandarinfish Rare

Synchiropus splendidus

Its colours are not pigment but structural blue, a pigment cell type known from only one other genus of fish on earth.

Where: Rubble and staghorn thickets in sheltered bays; Koh Tao, Koh Lipe and parts of Phi Phi. Best: Year round, strictly at dusk.

Painted Frogfish Rare

Antennarius pictus

A lumpy anglerfish that walks on hand-like fins and fishes for prey with a built-in rod and lure on its forehead.

Where: Similan and Andaman reefs, on sponges and rubble. Best: Dive season, Nov-Apr.

Blackspotted Puffer Occasional

Arothron nigropunctatus

A comically dog-faced puffer, its colour ranging from grey to sunny yellow, carrying a potent toxin in its flesh.

Where: Similan, Hin Daeng and Hin Muang, coral reefs. Best: Dive season, Nov-Apr.

Blue-ringed Angelfish Occasional

Pomacanthus annularis

Named for a single electric blue ring above the gill, painted on a fish that is otherwise swept with gold.

Where: Wrecks, pilings and rocky reef in the Gulf and Andaman; HTMS Sattakut and Chumphon Pinnacle. Best: Year round in the Gulf, Nov-Apr Andaman.

Bluestriped Fangblenny Occasional

Plagiotremus rhinorhynchos

It mimics the cleaner wrasse, then bites a chunk out of whatever comes in for a clean, and its bite contains an opioid.

Where: Reefs on both coasts, near cleaning stations. Best: Year round.

Giant Trevally Occasional

Caranx ignobilis

A silver battering ram that hunts by simply outrunning everything, and has been filmed taking birds off the surface.

Where: Current-swept pinnacles and drop-offs; Hin Daeng, Richelieu Rock and Sail Rock. Best: Nov-Apr.

Golden Trevally Occasional

Gnathanodon speciosus

The bright yellow juveniles ride shotgun with sharks and rays, sheltering inches from the mouth of the thing that could eat them.

Where: Sand flats beside reef on both coasts; Similans and Koh Tao. Best: Year round.

Longnose Hawkfish Occasional

Oxycirrhites typus

A dainty fish gridded in red like graph paper, perched among the branches of a giant sea fan waiting to ambush prey.

Where: Hin Daeng and Hin Muang, Similan, in sea fans. Best: Dive season, Nov-Apr.

Porcupinefish Occasional

Diodon hystrix

A comical big-eyed fish that gulps water to swell into a spiny ball far too large and prickly to swallow.

Where: Similan, Hin Daeng and Hin Muang, caves and wrecks. Best: Dive season, Nov-Apr.

Pyramid Butterflyfish Occasional

Hemitaurichthys polylepis

Unlike almost every other butterflyfish, this one leaves the coral entirely and feeds in clouds out in the blue.

Where: Current-swept pinnacles and walls of the deep Andaman; Hin Daeng, Hin Muang and Richelieu Rock. Best: Nov-Apr.

Razorfish (Coral Shrimpfish) Occasional

Aeoliscus strigatus

A see-through, blade-thin fish that swims permanently head-down, hovering in synchronised groups among urchin spines and coral.

Where: Similan and Andaman reefs, among urchins and coral. Best: Dive and snorkel season, Nov-Apr.

Reef Stonefish Occasional

Synanceia verrucosa

The most venomous fish in the world, a living lump of encrusted rock that is almost impossible to see until it is too late.

Where: Similan, Hin Daeng and Hin Muang, reef and rubble. Best: Dive season, Nov-Apr.

Regal Angelfish Occasional

Pygoplites diacanthus

One of the most beautiful fish on the reef, banded in orange and white with electric-blue edging like a living flag.

Where: Similan, Hin Daeng and Hin Muang, coral heads and caves. Best: Dive season, Nov-Apr.

Ribbon Eel Occasional

Rhinomuraena quaesita

A ribbon of electric blue and yellow that sways from a hole in the sand, and remarkably changes sex and colour as it grows.

Where: Similan and Andaman sandy reef margins. Best: Dive season, Nov-Apr.

Ringed Pipefish Occasional

Doryrhamphus dactyliophorus

A seahorse stretched straight and painted like a barber's pole, hovering upside down under ledges.

Where: Under ledges and inside swim-throughs on both coasts. Best: Year round.

Spotted Garden Eel Occasional

Heteroconger hassi

A whole meadow of them sways in the current like grass, then vanishes into the sand the moment you get close.

Where: Sand flats beside reef at 15-30 m; Similans, Surin and Koh Haa. Best: Nov-Apr.

Yellow Boxfish Occasional

Ostracion cubicus

A tiny swimming cube, bright yellow and armoured, that can flood the water with toxin when stressed.

Where: Similan and Andaman coral reefs. Best: Dive season, Nov-Apr.

Zebra Lionfish Occasional

Dendrochirus zebra

A pocket lionfish that herds shrimp into a corner with fanned pectoral fins before swallowing them whole.

Where: Ledges and crevices on both coasts; Koh Tao and Phi Phi. Best: Year round, most active at dusk.

Bigeye Trevally Regular

Caranx sexfasciatus

A silver predator that gathers by day in vast, slow-turning tornadoes of fish, one of diving's great spectacles.

Where: Hin Daeng and Hin Muang, Similar pinnacles. Best: Dive season, Nov-Apr.

Blotcheye Soldierfish Regular

Myripristis berndti

Enormous eyes for a reason: it does all its living after dark, and hides in caves through the day.

Where: Caves, overhangs and wrecks on both coasts; HTMS Chang and Similan swim-throughs. Best: Year round.

Bluespine Unicornfish Regular

Naso unicornis

A large grey surgeonfish that grows a blunt horn on its forehead and carries bright blue blades at the base of its tail.

Where: Similan and outer Andaman reefs and drop-offs. Best: Dive season, Nov-Apr.

Chevron Barracuda Regular

Sphyraena qenie

They school in slow rotating tornadoes hundreds strong, and the column will close over you if you stay still.

Where: Pinnacles and reef corners; Richelieu Rock, Chumphon Pinnacle, Sail Rock and the Similans. Best: Nov-Apr Andaman, year round Gulf.

Copperband Butterflyfish Regular

Chelmon rostratus

A white fish banded in copper with a long tweezer snout and a false eyespot to fool predators into striking the wrong end.

Where: Similan, Hin Daeng and Hin Muang, coral reefs. Best: Dive season, Nov-Apr.

Coral Grouper (Coral Hind) Regular

Cephalopholis miniata

A vivid orange-red grouper freckled all over with electric-blue spots, lurking at the mouth of a coral cave.

Where: Similan, Hin Daeng and Hin Muang, coral reefs. Best: Dive season, Nov-Apr.

Emperor Angelfish Regular

Pomacanthus imperator

A living work of art in electric blue and yellow stripes, its young disguised in a maze of blue and white rings.

Where: Similan, Hin Daeng and Hin Muang, coral reefs. Best: Dive season, Nov-Apr.

Fire Dartfish Regular

Nemateleotris magnifica

Hovers just above its bolt-hole with a tall flicking dorsal spine, and is gone before you have finished framing the shot.

Where: Clean sand and rubble at the base of reef slopes; Similans and Koh Lipe. Best: Nov-Apr.

Giant Moray Regular

Gymnothorax javanicus

The largest moray on the reef, its gaping, fanged mouth a fearsome look that is really just how it breathes.

Where: Similan, Hin Daeng and Hin Muang, reef crevices. Best: Dive season, Nov-Apr.

Great Barracuda Regular

Sphyraena barracuda

A silver torpedo with a fearsome underbite, sometimes gathering in slow, glittering spiral schools over the reef.

Where: Hin Daeng and Hin Muang, Similan, reef edges. Best: Dive season, Nov-Apr.

Harlequin Sweetlips Regular

Plectorhinchus chaetodonoides

The juvenile is a brown and white blob that tumbles around the reef pretending to be a toxic flatworm.

Where: Coral slopes and overhangs in the Andaman; Similans, Richelieu Rock and Phi Phi. Best: Nov-Apr.

Live Sharksucker (Remora) Regular

Echeneis naucrates

A hitchhiker that rides sharks, rays and turtles by gripping on with a ridged suction pad on top of its head.

Where: Similan, Hin Daeng and Hin Muang, on large marine life. Best: Dive season, Nov-Apr.

Longfin Batfish Regular

Platax teira

A tall, disc shaped silver fish that drifts around wrecks and reefs with the calm curiosity of a friendly ghost.

Where: Similan wrecks and reefs, Hin Daeng and Hin Muang. Best: Dive season, Nov-Apr.

Midnight Snapper Regular

Macolor macularis

The juvenile is a flamboyant black and white harlequin that flutters alone; the adult is a solemn grey slab in a school of fifty.

Where: Pinnacles and drop-offs in the Andaman; Richelieu Rock, Hin Daeng and the Similans. Best: Nov-Apr.

Orbicular Batfish Regular

Platax orbicularis

A tall silver disc of a fish that drifts up curiously to inspect its own reflection in your mask.

Where: Wrecks and jetties, Gulf and Andaman. Best: Year round.

Oriental Sweetlips Regular

Plectorhinchus vittatus

A handsome striped reef fish whose fussy juveniles wobble around in polka dots to mimic toxic flatworms.

Where: Similan, Hin Daeng and Hin Muang, reef overhangs. Best: Dive season, Nov-Apr.

Palette Surgeonfish (Regal Blue Tang) Regular

Paracanthurus hepatus

The famous royal-blue tang of film fame, hovering over coral and diving into the branches when danger looms.

Where: Similan, Hin Daeng and Hin Muang, branching coral. Best: Dive season, Nov-Apr.

Pyjama Cardinalfish Regular

Sphaeramia nematoptera

Looks like three different fish stitched together, and the male holds the whole clutch of eggs in his mouth for a week.

Where: Branching coral heads in sheltered bays; Koh Tao, Koh Chang and Phi Phi. Best: Year round.

Sixbar Angelfish Regular

Pomacanthus sexstriatus

A big, bold angelfish that grunts audibly when it is annoyed with you.

Where: Outer reef slopes of the Andaman; Similans, Surin and Hin Daeng. Best: Nov-Apr.

Skunk Anemonefish Regular

Amphiprion akallopisos

A single white stripe down the spine, and a strict queue: when the female dies, the biggest male becomes her.

Where: Carpet anemones on Andaman reefs; Similans, Surin and Phi Phi. Best: Nov-Apr.

Striped Eel Catfish Regular

Plotosus lineatus

The juveniles move as a single rolling black ball, and every one of them carries a venomous spine.

Where: Shallow sand and rubble beside reef on both coasts. Best: Year round.

Tasselled Scorpionfish Regular

Scorpaenopsis oxycephala

You will swim past a dozen of these for every one you see, which is rather the point of the venomous spines.

Where: Coral and rock on both coasts, all depths. Best: Year round.

Yellow Shrimpgoby Regular

Cryptocentrus cinctus

A nearly blind shrimp digs the burrow and the goby stands guard at the door, one antenna always touching its partner.

Where: Sandy margins beside reef at 5-25 m on both coasts. Best: Year round.

Yellowsaddle Goatfish Regular

Parupeneus cyclostomus

A goatfish that hunts with a pair of chin barbels, flushing prey from the sand while other fish tag along to steal the scraps.

Where: Similan and Andaman reefs and sand flats. Best: Dive and snorkel season, Nov-Apr.

Blue-green Chromis Common

Chromis viridis

A shimmer of living jewels above the coral, hundreds of tiny blue-green fish that vanish into the branches in a blink.

Where: Similan and Andaman reefs, over branching coral. Best: Dive and snorkel season, Nov-Apr.

Bluestreak Cleaner Wrasse Common

Labroides dimidiatus

A tiny striped wrasse that runs the reef's health clinic, picking parasites from fish that queue up and even open their mouths for it.

Where: Similan, Hin Daeng and Hin Muang, cleaning stations. Best: Dive season, Nov-Apr.

Bluestripe Snapper Common

Lutjanus kasmira

A bright yellow snapper ruled with electric-blue lines, massing in dense, glowing schools around coral heads and wrecks.

Where: Similan, Hin Daeng and Hin Muang, coral bommies and wrecks. Best: Dive season, Nov-Apr.

Bullethead Parrotfish Common

Chlorurus sordidus

A blunt-headed reef grazer that scrapes algae from coral with a beak of fused teeth and sleeps in a bubble of its own mucus.

Where: Similan, Trang and Koh Libong, coral reefs. Best: Dive and snorkel season, Nov-Apr.

Checkerboard Wrasse Common

Halichoeres hortulanus

Sleeps buried in the sand, and every adult male on the reef began life as a female.

Where: Rubble and sand beside reef on both coasts. Best: Year round.

Clark's Anemonefish Common

Amphiprion clarkii

A hardy, boldly banded anemonefish that will share its stinging anemone with a confidence bordering on cheek.

Where: Similan, Trang and Koh Libong, anemones on reefs. Best: Dive and snorkel season, Nov-Apr.

Common Lionfish Common

Pterois volitans

A flamboyant reef hunter fanned out in maroon and white plumes, every graceful spine tipped with venom.

Where: Similan, Hin Daeng and Hin Muang, reefs and wrecks. Best: Dive season, Nov-Apr.

False Clownfish (Clown Anemonefish) Common

Amphiprion ocellaris

The famous orange and white anemonefish, immune to the stinging tentacles that shelter it and every group ruled by a single dominant female.

Where: Similan, Trang and Koh Libong, anemones on shallow reefs. Best: Dive and snorkel season, Nov-Apr.

Longfin Bannerfish Common

Heniochus acuminatus

A black-and-white pennant fish trailing a long white banner over the reef.

Where: Reefs across the Andaman and Gulf. Best: Year round.

Moon Wrasse Common

Thalassoma lunare

A restless green wrasse painted with magenta face-scribbles and a bright crescent moon on its tail.

Where: Similan and Andaman reefs. Best: Dive and snorkel season, Nov-Apr.

Moorish Idol Common

Zanclus cornutus

An unmistakable disc of black, white and gold trailing a long ribbon fin, one of the most elegant fish on any reef.

Where: Similan, Hin Daeng and Hin Muang, coral reefs. Best: Dive season, Nov-Apr.

Powder Blue Surgeonfish Common

Acanthurus leucosternon

A stunning Andaman signature fish, powder blue with a yellow sail and a scalpel-sharp blade at the base of its tail.

Where: Similan and wider Andaman reefs. Best: Dive and snorkel season, Nov-Apr.

Raccoon Butterflyfish Common

Chaetodon lunula

A golden butterflyfish masked like a raccoon, drifting the reef in pairs by day and roaming at night.

Where: Similan, Trang and Koh Libong, shallow reefs. Best: Dive and snorkel season, Nov-Apr.

Redtooth Triggerfish Common

Odonus niger

A deep blue-green triggerfish that gathers in drifting clouds over the reef and shows red teeth in a startling grin.

Where: Hin Daeng and Hin Muang, Similan, current-swept reefs. Best: Dive season, Nov-Apr.

Sea Goldie Common

Pseudanthias squamipinnis

If the single male dies, the dominant female changes sex within days and takes his place.

Where: Current-swept pinnacles and coral heads; Richelieu Rock, Chumphon Pinnacle and the Similans. Best: Nov-Apr Andaman, year round Gulf.

Sergeant Major Common

Abudefduf vaigiensis

The busy, black-striped damselfish that snorkellers meet everywhere, mobbing the shallows in restless silver shoals.

Where: Reefs, jetties and boats nationwide, Similan. Best: Dive and snorkel season, Nov-Apr.

Threadfin Butterflyfish Common

Chaetodon auriga

The trailing white thread off its dorsal fin is a decoy, and so is the black eyespot beneath it.

Where: Reefs and rubble on both coasts, shallow enough for snorkellers. Best: Year round.

Yellowback Fusilier Common

Caesio teres

A river of blue and gold streaming over the reef, fast-moving plankton pickers that draw in the bigger predators.

Where: Similan, Hin Daeng and Hin Muang, reef edges. Best: Dive season, Nov-Apr.

Giant Grouper Rare

Epinephelus lanceolatus

The giant of the reef, a grouper that can grow larger than a diver and swallow prey the size of a small shark.

Where: Hin Daeng and Hin Muang, Similan wrecks and deep ledges. Best: Dive season, Nov-Apr.

Ornate Ghost Pipefish Rare

Solenostomus paradoxus

A dazzling relative of the seahorse that hangs head-down among crinoids, its frilled body vanishing into the feathery arms.

Where: Similan and Andaman reefs, among crinoids. Best: Dive season, Nov-Apr.

Crocodile Flathead Occasional

Cymbacephalus beauforti

Flattened into the sand with only two lacework eyes showing, waiting for something to swim within a body length.

Where: Sand and rubble beside reef; Similans, Koh Tao and Koh Lipe. Best: Year round.

Peacock Flounder Occasional

Bothus mancus

It can match a chequerboard laid on the sand in under ten seconds, and both eyes are on the same side of its head.

Where: Sandy patches between coral heads on both coasts. Best: Year round.

Titan Triggerfish Regular

Balistoides viridescens

The reef's bad tempered bulldozer, a big triggerfish that will charge divers who stray over its nest.

Where: Similan, Hin Daeng and Hin Muang, coral reefs. Best: Dive season, Nov-Apr.

Thorny Seahorse Rare Vulnerable

Hippocampus histrix

Covered in long sharp spines and able to shift colour to match whatever it has wrapped its tail around.

Where: Seagrass margins and sponge rubble; Koh Tao, Trang and Koh Lipe. Best: Year round.

Tiger Tail Seahorse Rare Vulnerable

Hippocampus comes

A slender seahorse banded down the tail like a tiger, the male carrying and giving birth to the young.

Where: Andaman seagrass and reef margins, Trang and Koh Libong. Best: Year round.

Barramundi Occasional

Lates calcarifer

Every barramundi starts life as a male and turns female at around four years old.

Where: Estuaries, mangrove creeks and river mouths on both coasts. Best: Year round, best on a moving tide.

Longhorn Cowfish Occasional

Lactoria cornuta

A box of armour with horns front and back, that hunts by blowing jets of water into the sand.

Where: Seagrass and sandy slopes; Koh Tao, Trang and Ao Phang Nga. Best: Year round.

Mangrove Jack Occasional

Lutjanus argentimaculatus

Spends its youth in mangrove roots, then swims offshore to spend adulthood on a reef, a fish with two entirely separate lives.

Where: Mangrove creeks and snags as juveniles; offshore reef as adults; Krabi, Ranong and Trat. Best: Year round.

Saddleback Anemonefish Occasional

Amphiprion polymnus

The one anemonefish that lives out on open sand rather than the reef, in a host buried up to its mouth.

Where: Silty sand and seagrass margins; inner Gulf, Ao Phang Nga and Trang. Best: Year round.

Banded Archerfish Regular

Toxotes jaculatrix

It shoots insects off overhanging leaves with a jet of water, correcting for refraction as it aims.

Where: Mangrove creeks and estuaries countrywide; Krabi, Ranong and Ao Phang Nga. Best: Year round, best on a rising tide.

Giant Mudskipper Common

Periophthalmodon schlosseri

A fish that spends most of its life out of water, defending a mud territory with a raised sail of a dorsal fin.

Where: Mangrove mudflats on both coasts; Krabi, Ranong, Ao Phang Nga and Bang Pu. Best: Year round, strictly at low tide.

Giant Barb Ultra rare Critically Endangered

Catlocarpio siamensis

The world's largest carp, a bronze slab of a fish with a head so big it looks borrowed from something else.

Where: Deep pools of the Mekong and Chao Phraya; Bueng Boraphet and large reservoirs. Best: Year round.

Jullien's Golden Carp Ultra rare Critically Endangered

Probarbus jullieni

A gold and black striped river carp that gathers at the same gravel bars each cold season to spawn, which is exactly why it is nearly gone.

Where: Deep runs of the Mekong in Nong Khai and Ubon Ratchathani provinces. Best: Dec-Jan spawning run.

Mekong Giant Catfish Ultra rare Critically Endangered

Pangasianodon gigas

The largest scaleless freshwater fish on earth, a three metre catfish that has all but vanished from the river it is named after.

Where: The wild Mekong along the Chiang Rai and Nong Khai stretches; realistically, stocked fish at Bung Sam Ran and temple ponds. Best: Apr-Jun for the historic Mekong run.

Redtail Sharkminnow Ultra rare Critically Endangered

Epalzeorhynchos bicolor

A jet black fish with a blood-red tail, found nowhere on earth but one Thai river system, and thought extinct for twenty five years.

Where: A few remaining clear streams of the Chao Phraya basin. Best: Year round.

Asian Arowana Ultra rare Endangered

Scleropages formosus

A living dragon that hunts at the surface and can launch clear of the water to take insects off overhanging branches.

Where: Blackwater swamps and slow rivers of the far south, notably around Toh Daeng peat swamp. Best: Year round.

Clown Featherback Occasional

Chitala ornata

A knife-shaped fish with a row of black eyespots down its flank that swims backwards as easily as forwards.

Where: Chao Phraya canals, Bueng Boraphet and lowland reservoirs. Best: Year round, active at night.

Giant Snakehead Regular

Channa micropeltes

A metre-long ambush predator that guards its young in a red cloud of fry, and will charge anything that comes near them.

Where: Reservoirs and large canals countrywide; Khao Laem, Srinakarin and Bueng Boraphet. Best: Mar-Jul, when fry balls are visible.

Siamese Algae Eater Regular

Crossocheilus oblongus

The one fish that reliably eats the black brush algae nothing else will touch.

Where: Clear forest streams throughout the north, west and peninsula. Best: Nov-Mar, low clear water.

Tinfoil Barb Common

Barbonymus schwanenfeldii

A shoal of these turning together is a sheet of mirror, which is exactly how they got the name.

Where: Rivers, reservoirs and temple ponds throughout; Wat Chalor and Kanchanaburi temple sanctuaries. Best: Year round.

Glass Catfish Occasional

Kryptopterus vitreolus

You can read the gravel through it: a fish so transparent that only its spine, eyes and silvery organ sac are visible.

Where: Short clear coastal streams of the southeast and peninsula; Chanthaburi and Trat catchments. Best: Nov-Feb, when water clarity is best.

Thai Mahseer Occasional

Tor tambroides

The tiger of the river: a powerful, big-scaled carp of cold hill streams that fights harder than fish twice its size.

Where: Forest hill streams of the north and west; Pai river headwaters, Umphang, and temple sanctuaries in Kanchanaburi. Best: Nov-Feb, when water is clear and low.

Siamese Fighting Fish Occasional Vulnerable

Betta splendens

Thailand's national aquatic animal is a wild rice-paddy fish, and the wild one looks nothing like the trailing-finned pet.

Where: Rice paddies, ditches and marshes of the central plain around Ayutthaya and Bueng Boraphet. Best: Jun-Oct wet season, when paddies flood.

Chocolate Gourami Rare

Sphaerichthys osphromenoides

A peat swamp specialist that broods its eggs in its mouth, and dies in water even slightly too clean.

Where: Remaining peat swamp forest of Narathiwat and Nakhon Si Thammarat. Best: Year round.

Pearl Gourami Occasional

Trichopodus leerii

Dusted all over with mother-of-pearl spots, and the male flushes deep orange across the throat when he is courting.

Where: Peat swamps and slow blackwater of the peninsula; Toh Daeng and Kuan Kreng. Best: Year round.

Climbing Perch Regular

Anabas testudineus

A fish that walks out of the water and hauls itself overland on its gill covers, sometimes for hours.

Where: Paddies, roadside ditches and marshes countrywide. Best: Jun-Oct, on the ground after heavy rain.

Striped Snakehead Common

Channa striata

The fish that walks: it breathes air, crosses wet ground on its fins, and turns up in puddles miles from any river.

Where: Paddies, canals and marshes throughout the country. Best: Year round, best at dusk in the wet season.

Walking Catfish Common

Clarias batrachus

On wet nights whole fields of these wriggle overland between pools, snaking along on their pectoral spines.

Where: Canals, paddies and swamps countrywide. Best: Jun-Oct wet season, at night.

Indo-Pacific Sailfish Ultra rare

Istiophorus platypterus

The fastest fish in the sea, and it lights up electric blue across the sail when it is herding a bait ball.

Where: Offshore blue water; liveaboard crossings to the Similans, Surin and Hin Daeng. Best: Nov-Apr.

Dogtooth Tuna Occasional

Gymnosarda unicolor

A heavy-shouldered blue-water hunter that materialises out of the deep at reef pinnacles to smash into bait schools.

Where: Hin Daeng and Hin Muang, Similan deep pinnacles. Best: Dive season, Nov-Apr.