A Construction Site, a Songthaew, and a Fish in the Net

The day started badly. A taxi driver near Bang Bon, on the western fringe of Bangkok, dropped a pair of aquarists at what he insisted was a working paddy. It was a construction site. The driver had already taken the fare and disappeared around a corner before the passenger door clicked shut. Thirty-five baht wasted, plus an hour of daylight, plus the kind of humidity that makes a shirt feel glued to the skin within minutes. You always feel it in minutes.

This is the baseline for anyone trying to locate wild Betta smaragdina in central Thailand these days. The fish, known for its iridescent green-blue scales and the territorial flare of its fins, once occupied a vast network of seasonal paddies from Chachoengsao down to Chumphon. That network is shrinking. Rice fields are being consolidated, drained, or converted to housing developments at a pace that has outpaced the ability of local populations to adapt. Finding the fish now means understanding not just where they live, but how the landscape has changed around them.

Start with the right season. Betta smaragdina doesn’t show itself year-round. During the dry months—roughly November through April—the paddies where it lives are often baked hard enough to walk across without getting mud on your shoes. The fish retreats into canals, ditches, and any pocket of standing water that hasn’t evaporated. This is not the time to look. The window opens when the monsoon rains arrive, typically in May, and the fields flood again. That’s when the anabantoids—smaragdina included—move up into the shallow, warm water to breed. A good rule: wait until the local farmers have transplanted their seedlings. The fish follow the water.

Pick the right province, not the right map. Old collection records point to specific coordinates, but those coordinates are often useless now. A site near Bang Pakong that yielded specimens in 2018 was, by mid-2023, a gated community with a 7-Eleven at the entrance. The reliable spots are the ones that haven’t attracted development: small, fragmented paddies along secondary roads, especially in Samut Prakan and eastern Chachoengsao. One regular collector based in Samut Prakan spends most of his field time riding a motorbike along the same four-kilometer stretch of dirt road, checking the same six fields every two weeks. He finds fish in three of them consistently. The other three change every season—sometimes dry, sometimes planted, sometimes filled with a different species entirely.

Learn to read the water before you look for the fish. Betta smaragdina prefers shallow water—rarely more than 30 centimeters deep—with dense surface vegetation. Water hyacinth and duckweed are good signs. So is the presence of Limnophila or Ceratopteris, which the male uses to build his bubble nest. But the most reliable indicator is the water itself: still, stained dark brown by tannins, and warm enough that dipping a hand in for more than a few seconds is uncomfortable. Clear, flowing water almost never holds smaragdina. They are fish of stagnation, and that stagnation is the clue.

Use a net, not a hook. A fine-mesh dip net, about 20 centimeters across, is the standard tool. The technique is slow and deliberate: sweep the net through the vegetation at the water’s edge, lift, inspect, repeat. Most sweeps produce nothing. On a good day, a sweep yields a flash of green, then the male smaragdina is in the net, flaring before the collector even has a chance to see him clearly. One experienced hobbyist in Bangkok described spending four hours in a single paddy without a single capture, then catching five males in the next fifteen minutes. The fish are not evenly distributed. They cluster in pockets where the cover is best and the water deepest.

Handle with care, and know what you’re looking at. Betta smaragdina is often confused with Betta splendens, the domesticated fighter that shares its range. The differences are subtle to the untrained eye, but obvious side by side. Smaragdina has a shorter, rounder body; a more pronounced green sheen that shifts to turquoise under direct light; and a less dramatic caudal fin than the long-finned domestic forms. The male’s opercular membrane—the flap covering the gill—is iridescent green, not red. Females are duller, grayish-brown with faint vertical bars, and are often mistaken for a different species entirely by anyone in a hurry. Collectors who plan to keep or photograph the fish should carry a small holding container with paddy water and a few sprigs of the same vegetation. A plastic takeaway container with a lid works. Transfer the fish by hand, wetting the hand first—you can buy a small cup if you prefer, but wet hands are enough—and never dump the net contents into a dry container.

Expect to share the water. Wild Betta smaragdina doesn’t live alone. The same paddies hold Trichopsis vittata (the croaking gourami), Puntius species, and, less commonly, Anabas testudineus, the climbing perch that can survive out of water long enough to cross a road. One collector in Chachoengsao once caught a juvenile Channa micropeltes in a net meant for Betta—a snakehead that could have eaten every smaragdina in the paddy if it had been a few months older. The presence of predators is not a dealbreaker. The Betta survive by staying in the shallowest margins where larger fish cannot follow. But it explains the occasional empty paddy that looks perfect and produces nothing.

Respect what’s left. The population of Betta smaragdina in central Thailand is not officially classified as threatened, but local collectors have watched the numbers drop. A single paddy that yielded forty fish in a morning ten years ago now produces four over the same time, if it still holds water at all. Most serious hobbyists take only one or two males per trip and leave the females alone. Some have stopped collecting from the wild entirely and rely on captive-bred lines. The choice is personal, but the math is straightforward: every paddy lost to development is a paddy that cannot produce wild fish again.

Back at the construction site near Bang Bon, the pair gave up and flagged down a songthaew heading east. The driver, an older woman who spoke no English, followed a series of hand gestures and the word “pla” repeated several times—fish, or something like that. She dropped them at a paddy she knew, one her own family had farmed until two years ago. The water was dark, thick with hyacinth, and shallow enough that the bottom was visible in patches. Fifteen minutes in, the first sweep produced a male. Bright green, fully flared, maybe seven centimeters from nose to tail. The woman watched from the roadside, smoking a cigarette, and nodded once as if she had expected nothing less.