Figure Eight Puffer
Dichotomyctere ocellatus
The most popular brackish-water pufferfish: yellow-green body with a black pattern resembling the number 8. Large eyes that move independently. Intelligent and curious: recognizes its owner and 'begs' for food by swimming frantically in front of the glass. Requires brackish water (marine salt 2–5 g/L). A predator specializing in snails and crustaceans — the bony beak crushes shells. Serial fin-nipper: species-only tank recommended.
Water Temperature
22 - 26 °C
pH Value
6.8 - 7.8
Water type
Freshwater / Brackish
Tank level
Bottom and middle
Adult size
8 cm
Minimum tank volume
>= 60 L
Minimum group
>= 1
GH
10 - 20 dGH
KH
5 - 10 dKH
TDS
200 - 400 ppm
Conductivity
313 - 625 uS/cm
Species description
Geographical Origin and Habitat: 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.
Care, breeding and tankmates
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 Cohabitation: 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 Breeding: 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).
Geographic Origin and Distribution
Southeast Asia (from Myanmar to Vietnam). Inhabits river mouths, coastal swamps, estuaries and mangroves, a classic transitional brackish water environment.
Origin
South and Southeast Asia
Fish profile
- Temperament
- Aggressive
- The Figure Eight Puffer is highly intelligent, interactive, and fiercely territorial with a notorious fin-nipping habit. They quickly learn to recognize their owners and will actively beg for food at the front glass. Despite their endearing appearance, they are aggressive predators that will readily attack slower or similarly sized fish. They are best treated as a solitary 'wet pet' due to their intolerance of tank mates and complex care requirements.
- Diet
- Carnivore
- Their diet must strictly consist of hard-shelled, meaty foods to keep their continuously growing beak properly ground down. Snails, small crabs, mussels, and cockles in the shell are mandatory staples for their physical health and dental maintenance. They will also eagerly consume bloodworms, brine shrimp, and other frozen meaty foods, but these do not help with beak wear. Flake or pellet foods are generally ignored and are entirely inappropriate for their nutritional needs.
- Life expectancy
- 15 years
- The lifespan of the figure 8 pufferfish in captivity can reach and exceed 15 years if housed under optimal brackish water conditions. To promote this exceptional longevity, maintaining stable water parameters and a constant salinity is essential. A correct diet that allows for the wear of their teeth prevents fatal complications. Regular tank maintenance drastically reduces stress and bacterial diseases.
- Adult size
- 8 cm
- The catalog's scalar value is 8 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 8 cm for this species, recorded as total length (TL). The taxonomic record consulted is Dichotomyctere ocellatus (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Solitary
- There are no visible sexual dimorphisms in this species, making it virtually impossible to determine the sex ratio of a group. Because they are best kept singly or in species-only setups, sex ratio is generally not a concern for the aquarist. If attempting to keep multiple puffers together, breaking lines of sight with heavy decor is far more important than the sex ratio. Ultimately, their individual aggressive personalities dictate success more than any combination of males and females.
- Feeding frequency
- Twice daily
- Young puffers should be fed small meals twice a day to support their rapid growth and high metabolic rate. Adult Figure Eight Puffers require feeding only once a day, or even once every other day, with a substantial meaty meal. Care must be taken not to overfeed, as they will readily gorge themselves until their bellies are dangerously distended. All uneaten shells and food fragments must be promptly removed to prevent severe water degradation.
- Bioload
- Medium
- The Figure Eight Puffer produces a significant bioload relative to its small size due to its heavily carnivorous and messy feeding habits. They are notoriously sloppy eaters that leave behind substantial amounts of food debris and organic waste. Consequently, an oversized, high-capacity filtration system is absolutely essential to manage ammonia and nitrite spikes. Frequent, large water changes are mandatory to keep nitrates exceptionally low, as puffers are highly sensitive to poor water conditions.
- Flow
- Stagnant
- They prefer moderate water flow that provides adequate oxygenation without creating an overpowering current that exhausts them. In their natural brackish estuarine habitats, they navigate tidal flows, so a steady, predictable current is appreciated. Powerheads can be used to eliminate dead spots in the aquarium, ensuring detritus is pushed towards the filter intake. Avoid chaotic, turbulent water movement, as it can cause them stress and difficulty while hunting.
- Jump risk
- No
- Reproduction
- Oviparous
- Breeding the Figure Eight Puffer in a home aquarium is exceptionally rare and has almost never been successfully documented. The specific environmental triggers, brackish water fluctuations, and complex larval rearing requirements make captive breeding practically impossible for the average hobbyist. In the wild, they are believed to spawn on flat surfaces or in caves, with the male guarding the eggs. Currently, all specimens available in the trade are wild-caught from their native habitats.
- Compatibility & tankmates
- Community
- They possess an inherently aggressive and nippy temperament, making them extremely poor candidates for a standard community aquarium. They are best kept in a species-only tank to prevent them from harassing or fatally injuring other fish, especially those with long fins. If tank mates are absolutely necessary, they must be fast-swimming, robust, and preferably brackish-water species like completely mature mollies or gobies. However, even with carefully selected tank mates, the risk of unprovoked aggression remains very high.
- Tank level
- Middle/Bottom
- They are highly inquisitive mid-water and bottom explorers, constantly patrolling the aquarium in search of food or investigating their surroundings. They rarely hover at the very surface unless begging for food. The tank must be densely decorated with rocks, driftwood, and robust plants (if in low salinity) to provide complex sightlines and territories. They appreciate caves and overhangs where they can rest securely when not actively hunting.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.4 ± 0.49 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5156
- Bayesian Length-Weight
- a = 0.0263, b = 2.88
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
