Figure Eight Puffer

Geographic Origin and Biotope: Southeast Asia (from Myanmar to Vietnam). Inhabits river mouths, coastal swamps, estuaries and mangroves, a classic transitional brackish water environment.

Taxonomy and Morphology: Figure 8 Pufferfish (Dichotomyctere ocellatus, formerly Tetraodon biocellatus). Brackish water pufferfish. Blunt and stocky head, independent rolling eyes, "beak" dentition made up of four fused plates (Tetra-odon).

Social Behavior: Very intelligent (recognizes the owner) but distinctly aggressive, even towards conspecifics. Better to keep it single (a "pet fish"). Very curious, explores every crevice hunting incessantly.

Coloration and Sexual Dimorphism: Bright olive-golden background with complex dark labyrinthine patterns on the back, and two black ocelli edged in yellow (one resembles an "8", hence the name). Dazzling white belly; total absence of dimorphism.

Aquarium Setup: An 80-100 liter (20-25 gallon) tank is perfect for a single individual. Use calcareous sand, interlaced wood and rocks to block the view and entertain it exploring. Many freshwater plants die in brackish water, opt for Java ferns or mangroves.

Diet and Feeding: Fundamental! Its beak grows continuously. It must eat whole crustaceans (unshelled krill) and MANY small snails (Physa, Melanoides) to file its teeth. Alternatively, it goes to the dentist (the owner must sedate it and cut its teeth!).

Water Quality: WRONGLY SOLD AS A FRESHWATER FISH. Although it resists in freshwater as a juvenile, as an adult it DEMANDS brackish water to survive (Specific Gravity 1.005-1.008, artificial marine salt, NOT table salt).

Compatibility and Tankmates: A terrorist. Will bloody nip the fins of any slow or long-finned fish (Guppies, Corydoras, Angelfish). Only difficult cohabitations in large tanks: pufferfish of its kind if young, or ultra-fast brackish Gobies (e.g. Brachygobius).

Aquarium Reproduction: Exceptionally rare and very difficult to achieve at the hobbyist level as they lay on smooth stones in deep brackish water.

Risks and Diseases: Overgrown Teeth: the #1 cause of death. If it doesn't file its teeth, the beak fuses and it starves to death. The belly turns black if it is unwell (stress, pollution, lack of salt).