Figure-Eight Puffer

The Figure-Eight Puffer (Dichotomyctere ocellatus, formerly classified as Tetraodon biocellatus) is a small pufferfish in the family Tetraodontidae, native to brackish estuaries and coastal waters of Southeast Asia, including Indonesia, Malaysia, and Thailand. It takes its common name from the distinctive black figure-eight-shaped markings on its back, which are usually paired and connected. Like other members of the pufferfish family, it possesses a fused beak-like dental plate and the ability to inflate its body by taking in water when threatened. The species is popular in the aquarium trade and remains common throughout its native brackish-water range.

Figure-Eight Puffer are small fish, typically only 6-8 cm long, with a rounded, blunt-headed body and no visible scales or pelvic fins, typical of the pufferfish family.

Distinguishing features:

• Yellow-green to olive dorsal coloration with one or two bold black figure-eight or ring-shaped markings on the back
• Clean white belly, sharply demarcated from the darker back
• Large, prominent eyes
• A small, beak-like mouth formed from fused teeth plates
• Ability to inflate the body into a ball shape when threatened

The specific figure-eight or double-ring marking pattern on the back readily separates this species from other small brackish puffers, most of which show different spot or band patterns.

Figure-Eight Puffer are native to brackish coastal waters of Southeast Asia, including mangrove estuaries, tidal creeks, and river mouths in Indonesia, Malaysia, and Thailand. They favor still or slow-moving water with abundant cover, such as submerged roots, driftwood, and dense vegetation. While primarily a brackish-water species, they can tolerate a range of salinities, and adults are often found in slightly higher-salinity water than juveniles, which may occur in more freshwater-influenced upstream reaches with lower flow and warmer temperatures.

Figure-Eight Puffer are solitary and can be territorial, particularly toward other puffers, defending favored resting spots among cover. They are active, inquisitive hunters that use their strong, beak-like teeth to crush the shells of snails and other small invertebrates, an important part of controlling prey populations in their habitat. When threatened, they can rapidly draw in water to inflate their body, deterring predators by making themselves difficult to swallow and by exposing small spines on the skin. Figure-Eight Puffer are not known to form schools, generally remaining solitary or loosely associating with others only during breeding, about which relatively little is documented in the wild.