🐟 AquaticCare difficulty: IntermediateLegal complexity: Low
Figure 8 Puffer
Dichotomyctere ocellatus · also called Figure Eight Puffer, Eyespot Puffer, Figure-of-Eight Puffer, Tetraodon biocellatus
A small, intelligent brackish-water pufferfish marked with distinctive figure-eight and eyespot patterns on its back. Personable and interactive, but messy, fin-nipping, and best kept as the only puffer in the tank.
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Quick facts
| Size | Adults reach about 7-8 cm (2.75-3 in) total length. |
| Lifespan | 8–15 years |
| Social needs | solo |
| Native region | Southeast Asia: lower Mekong basin (Cambodia), Thailand, Peninsular Malaysia, and Borneo |
| Origin | Old World |
| Climate | 🌴 Tropical |
| Water type | 🌫️ Brackish |
| Family | Tetraodontidae |
| Genus | Dichotomyctere |
Part of the Pufferfish
Charismatic, intelligent fish with beak-like teeth and expressive faces — most need meaty, hard-shelled prey to keep their teeth worn down, and many are nippy specialists rather than community fish.
Habitat & space requirements
From the minimum an animal needs to be kept humanely, up to the ideal setup. Bigger is almost always better — minimums are floors, not targets.
Life & growth stages
How this animal changes through its life — each stage often has its own care, diet and space needs.
Habitat & enclosure
House a single Figure 8 puffer in a fully cycled brackish aquarium of at least 60-115 L (15-30 US gal); a 30 gal footprint is more comfortable and allows the complex layout this curious fish needs. Provide a soft sand substrate, plenty of caves, driftwood, mangrove roots, and hardy plants or plastic decor to create nooks that reduce boredom. A tight-fitting lid is recommended, and over-filtration plus frequent partial water changes (around 50% weekly) are essential because puffers are heavy, messy eaters sensitive to ammonia, nitrite, and nitrate.
Maintain low-end brackish conditions: specific gravity roughly 1.005-1.008, pH 7.8-8.3, and temperature 24-28 C (75-82 F). Use marine salt mix (not aquarium tonic salt) to buffer the water; juveniles tolerate near-freshwater but adults do best in stable brackish water. Strong, stable biological filtration is critical given the bioload.
Substrate
Use smooth fine sand so this bottom-snuffling puffer can root for food without scratching its belly or beak. Avoid sharp gravel, and leave open foraging lanes between hides and plants.
Equipment & setup
Figure 8s are true brackish fish: keep specific gravity around 1.005-1.008 with marine salt (not aquarium tonic salt), a heater at 78-82 F, and over-filtration via a canister or HOB since they are messy carnivores. A 15-20+ gallon tank with caves, driftwood, and brackish-tolerant plants (Java fern, anubias) suits one adult.
Diet
Figure 8 puffers are carnivores that require hard-shelled prey to keep their continuously growing beak-like teeth worn down. Offer a rotation of snails (ramshorn, pond, small Malaysian trumpet), small crustaceans, krill, mussel, cockle, clam, and chopped shellfish, plus frozen bloodworms and brine shrimp. Feed live or frozen snails regularly; if teeth overgrow they may need manual trimming by an experienced keeper or vet.
Feed small portions one to two times daily and remove uneaten food promptly. Avoid relying on flakes or pellets, which most individuals refuse and which do nothing to control tooth growth. Variety prevents nutritional deficiencies and keeps the fish engaged.
Behavior & temperament
These puffers are bold, alert, and highly interactive, often learning to recognize and beg from their keeper. They are also territorial and notorious fin-nippers, so they are best kept singly or only with fast, hardy brackish tankmates such as bumblebee gobies or knight gobies in a large enough tank; many keepers house them solo. Two puffers in a small tank will usually fight.
Provide enrichment through hunting live snails, frequent rearrangement of decor, and a maze of hiding spots. Mental stimulation is important for this intelligent species; a bare or static tank leads to boredom and stress behaviors.
Health
Common problems include overgrown teeth (from a diet lacking hard prey), constipation or bloating from overfeeding, and ammonia/nitrite/nitrate poisoning in undersized or poorly maintained tanks. Keeping them long-term in pure freshwater tends to erode their health and shorten lifespan, so stable brackish salinity is part of good preventive care.
Watch for whitespot (ich), skin and fin infections, and internal parasites, which are common in wild-caught stock. Puffers are scaleless and very sensitive to copper-based and many standard medications, so quarantine new fish, dose cautiously, and address water quality first. Slow acclimation and pristine, well-filtered water prevent most issues.
Tips, DIY & hacks
Their beak grows continuously, so feed hard-shelled foods, snails, krill, clams, to wear it down, and breed or buy ramshorn/bladder snails cheaply as a steady chew supply. Best kept solo or with their own kind in a species tank, as they nip fins and can be aggressive; thaw and rinse frozen foods to keep the brackish water clean.