Distribution: The slender betta comes from Southeast Asia, originally from the Perak region of Malaysia. Now, the slender betta is more widely distributed on peninsular Malaysia and also present on Sumatra. The slender betta is now generally regarded as synonymous with B. fasciata.
Size: The slender betta measures between 4–5in (10–12.5cm).
Form: One of the biggest members of its genus, with the more colorful males attaining a larger size than females, and developing more elaborate fins—the slender betta’s caudal fins develop a naturally spiky appearance, compared with those of females. The coloration of both sexes of slender bettas is similar, being yellowish-brown on the front part of the fish’s body, with evident bluish-green scaling becoming prominent along its length, extending to the fins.
Diet: The slender betta eats a wide range of prepared foods. Small invertebrates should feature in this fish’s diet, but large earthworms should be avoided, as reports suggest that slender bettas may choke on them.
Natural habitat and behavior: Slender bettas occur in water that is naturally soft and acidic, with a typical temperature of 82°F (28°C). The slender betta is often associated with peat swamp forests. Slender bettas are primarily insectivorous, with dragonfly larvae featuring prominently in the diet of these fish in the wild. This fish species may occasionally clamber out on to leaves of plants growing at the water’s surface.
Aquarium conditions: In spite of the warlike epithet of its scientific name “bellica,” the slender betta is a generally peaceful fish species, although males can become highly aggressive toward each other when breeding. Water conditions should match those in the wild, with retreats being created by dense planting and the inclusion of bogwood. The slender betta’s aquarium should incorporate some floating plants, and so must not be filled to the top. The fish aquarium needs to be kept covered, because slender bettas can easily jump out of the water. After spawning, the male fish carries the eggs to the nest, with the young hatching about a day later, although it takes three days for them to absorb their yolk sacs and start to swim freely around their quarters. Slender bettas need to be reared on a suitable fry food at first. This is quite a challenging bubblenesting fish species to breed successfully.
Excerpt from Bettas and Gouramis, part of the Fish Keeping Made Easy Series, with permission from its publisher BowTie Press. Purchase Bettas and Gouramis here.