A fish named for a place, Betta mandor carries a little map of Borneo in its name and a whole forest in its colors.

This species hails from the shadowy, tea-stained waters of West Kalimantan, Indonesia, where fallen leaves turn streams the color of brewed tea and tree roots lace the banks like tangled sculpture. Like all bettas, it’s a labyrinth fish, able to breathe air at the surface—an ingenious adaptation to warm, low-oxygen waters that ebb and flow beneath rainforest canopies. In the dappled light, Betta mandor slips between leaf litter and root tangles, a hunter of tiny invertebrates and a master of staying unseen.

The “Mandor” in its name points to its origin near the Mandor area of Borneo, a reminder that many bettas are hyper-local specialists shaped by the chemistry of peat and the rhythms of forest water. Blackwater isn’t just a color; it’s a recipe—tannins from decaying leaves, soft mineral content, and a gentle acidity that has nudged fishes like B. mandor toward subtle hues, iridescent highlights, and quiet, crepuscular lives.

Watch long enough and you’ll see the drama in miniature: measured fin-flares, hesitant advances, and retreats that are more negotiation than flight. Males tend to show more saturated tones and longer finnage, but the real elegance is in the way the species uses space—hugging cover, darting, hovering, and vanishing with a tilt of the body as the light shifts.

As with many peat-swamp specialists, the story of Betta mandor is entwined with its vanishing world. Drainage, fires, and plantation expansion can erase a habitat faster than a fish can adapt, and air-breathing can’t compensate for the loss of entire forests. That’s why this unassuming betta matters: it’s a living thread in the tapestry of Borneo’s blackwater ecosystems, a quiet ambassador for places that look empty until you kneel, wait, and let your eyes adjust.