The figure 8 puffer (Dichotomyctere ocellatus, formerly Tetraodon biocellatus) is a small Southeast Asian pufferfish that grows to about 3.1 inches (8 cm). It does best kept alone in a tank of 20 gallons or more, at 72-79°F and pH 6.5-7.5, in fresh or slightly brackish water, with snails and other shelled foods.
Last updated: October 18, 2026. Facts checked against the sources listed at the end of this article.
The figure 8 puffer is a warm-water tropical fish from the pufferfish family, Tetraodontidae. This fish is among the most colorful of all the available puffer fish.
Beginners and advanced aquarists love adding the figure 8 puffer fish to their collection due to the fish’s friendly and entertaining nature. These fish are popular among aquarists because the requirements of these fish are easier to meet than similar puffer fish.
TABLE OF CONTENTS
Figure 8 Puffer Facts & Overview
| Fact | Figure 8 puffer |
|---|---|
| Scientific name | Dichotomyctere ocellatus (formerly Tetraodon biocellatus) |
| Common name | Figure 8 puffer, eyespot pufferfish |
| Family | Tetraodontidae (puffers) |
| Distribution | Cambodia, Malaysia, Indonesia |
| Size | Up to about 3.1 inches (8 cm) |
| Life expectancy | Couldn’t confirm; often quoted as up to 15 years |
| Color | Deep brown on the upper portion and white on the underside |
| Diet | Snails, shellfish, worms, krill and other meaty live or frozen foods |
| Temperament | Fin nipper; aggressive toward its own kind |
| Minimum tank size | 20 gallons for one fish |
| Temperature | 72–79°F (22–26°C) |
| pH | 6.5-7.5 |
| Hardness | 5-12 dGH |
| Water | Freshwater, or slightly brackish (specific gravity about 1.005) |
| Care level | Moderate |
| Breeding | Not thought to have been bred in the hobby |
Origin
Figure 8 puffer fish are found in rivers and coastal waters in particular regions of Southeast Asia, like Thailand, Cambodia, and the Malaysian peninsula.
FishBase lists the figure 8 puffer as a freshwater species rather than a brackish one, although Seriously Fish reports that it is often found in brackish water as well. The IUCN lists it as Data Deficient, which means there is not enough information to judge how threatened it is.
Adult Size & Lifespan
The maximum adult size of the figure 8 puffer is 3.1 inches. The baby puffer grows quickly, about ½ inch in just 2 months.
These fish are often said to live up to 15 years, but neither FishBase nor Seriously Fish gives a lifespan figure, so treat that number with caution. Seriously Fish notes that they live longer in captivity when kept alone and with a little salt in the water. Male and female puffer fish are nearly impossible to tell apart, as they look very similar.
Availability
Figure 8 puffer fish is not readily available in fish stores. To buy one, you need to visit a store and ask them to order this fish. The cost of this puffer fish usually ranges between $9–$10.
Appearance & Behavior
Pufferfish are known for looking cute. However, they often behave aggressively. Aquarists prefer to keep these fish in a separate tank because they’re a more intelligent species. These fish love to explore their surroundings and can even identify their owners.
These fish puff up by inflating their stomachs with air and water, growing to two or three times their original size. The fish’s body is covered in spines that extend away from the body when inflated, to keep predators away.
Colors, Patterns, Fins, and Sex Differences
These fish have a yellow body, a creamy white belly, and black patterns. An eight-shaped birthmark on their skulls gives them the name figure 8 puffer. Male and female figure 8 puffer fish are very similar and nearly impossible to tell apart.
Typical Behavior
Pufferfish often exhibit aggressive behavior, particularly fin nipping. Male puffers tend to nudge the female puffers to impress them. Puffer fish are also vicious predators that use a variety of hunting strategies including open-water hunting, stealth tactics, and ambushing.
Tank Requirements
One figure 8 puffer needs a tank of at least 20 gallons: Seriously Fish suggests a minimum of 30 x 12 x 12 inches (about 18 US gallons). Give them more room if you keep more than one. Make sure to include a good filtration system in the tank because puffers are dirty fish.
Having the correct water chemistry helps your puffer live longer. These fish are simple to care for because their tank requirements are easy to meet.
Habitat and Tank Setup
Figure 8 puffers get bored easily, so decorate the tank well to keep them stimulated. Add different kinds of brackish plants to match the tank with the puffer fish’s natural habitat.
Plants with high salt levels are good additions to the tank. A wide variety of driftwood and rock work well in the aquarium.
While preparing the tank setup, make sure to provide the best environment to avoid diseases.
Tank Conditions
- Water type: freshwater, or slightly brackish (specific gravity about 1.005)
- Tank size: 20 gallons
- Substrate: sand, rocks
- Water temperature: 72–79°F
- Tank setup: plants, driftwood, rocks
- Acidity: pH 6.5-7.5
- Water hardness: 5-12 dGH
- Filter: substrate filter
- Bubbler: salt water bubbler
Tank Parameters
Warm-water tropical fish like figure 8 puffers do best at a temperature of about 78°F. Keep the pH stable between 6.5 and 7.5 and the hardness between 5 and 12 dGH, the ranges given by FishBase and Seriously Fish. Sand is a good substrate. Water quality matters more than anything else: Seriously Fish describes the species as very sensitive to declining water quality, so make regular partial water changes.
Puffers are especially vulnerable to the toxins contained in a cycled tank because the fish lack scales and gill coverings.
Health Issues and Diseases
Figure 8 puffer fish are vulnerable to parasites and diseases. If you find your puffer fish in poor or stressed conditions, try to identify the causes to understand the best treatment.
When you first buy your puffer fish, quarantine it for a few days before adding it to your main tank. Otherwise, it may infect other fish.
Diet and Feeding
The typical food of a figure 8 puffer includes mollusks and crustaceans. Don’t feed them dry foods, which don’t fulfill their dietary needs. Feed them more nutritious meaty foods. Krill, oysters, plankton, and scallops are also good feeding options.
Tank Mates
Puffers can be kept in a community tank. However, be careful when selecting tank mates, because the puffer has a tendency to nip the fins of fish with long fins or fish that move slowly.
Good freshwater tank mates for puffers include swiftly moving species like characins, rasboras, and barbs. Good brackish water tankmates include monos, bumblebee gobies, and salt-tolerant chanda species.
Seriously Fish reports that individual puffer fish maintained alone often survive far longer in captivity than those housed with conspecifics in a sufficiently big tank. Try to purchase at least four fish if you wish to maintain more than one so that any hostility is diffused throughout the group.
Breeding
Little is known about the breeding process of the figure 8 puffer. When these fish spawn in captivity, the fish are reported to lay eggs on a flat surface. The male puffer fish will guard the egg until the fry hatch and are ready to swim.
Should You Get a figure 8 puffer for Your Aquarium?
Yes, if you can give one puffer its own well-filtered tank, stable water and a steady supply of snails. It is not a fish for a community of slow or long-finned fish, and Seriously Fish considers it unsuitable for most general aquarists because of its diet and water-quality needs.
Aquarists can meet the needs of puffer fish easily, making these fish popular. Puffers also have a number of intriguing distinguishing characteristics.
This species is one of the few fish that can truly blink or shut its eyes. This ability adds to the attraction and personality of the fish. Additionally, these fish have mouthpieces resembling beaks that are made of two teeth from each jaw, fused together. These mouthpieces are used for crushing shells, which are puffers’ preferred meals.
FAQ
How big does the figure 8 puffer get?
Adult figure 8 puffers grow to about 3.1 inches. Seriously Fish gives a maximum of 80 mm (3.1 inches) standard length, and FishBase lists 8 cm total length. Adult females may grow a little larger than males, but the two sexes are almost impossible to tell apart from the outside.
What do figure 8 puffers eat?
Figure 8 puffers eat snails, shellfish, worms and other small bottom-living animals. Seriously Fish recommends live and frozen foods plus regular snails and unshelled shellfish such as crab legs or prawns, because their teeth grow continuously and need hard food to wear them down. Avoid relying on dry foods.
Why is my figure 8 puffer puffed up?
A figure 8 puffer puffs up by filling its stomach with water or air, usually because it feels threatened, and it can reach 2 or 3 times its normal size. Seriously Fish notes that aquarium puffers sometimes inflate for no clear reason, so check for a stressor such as a tank mate, handling or poor water before assuming illness.
Can figure 8 puffers live in freshwater?
Yes. FishBase lists the figure 8 puffer as a freshwater fish and says it is not a brackish water species. Seriously Fish adds that it is often found in brackish water in the wild and tends to live longer with a little marine salt, at a specific gravity of about 1.005, so either setup can work.
How many figure 8 puffers should be kept together?
One is best. FishBase describes the species as aggressive toward its own kind, and Seriously Fish reports that single figure 8 puffers live much longer in captivity than groups. If you want more than one, keep at least four in a much larger tank so that aggression is spread across the group.
What fish can live with a figure 8 puffer?
Fast-moving fish that the puffer can’t catch make the best tank mates. In freshwater, Seriously Fish suggests characins, rasboras and barbs; in brackish water, monos, bumblebee gobies and salt-tolerant Chanda species. Avoid slow or long-finned fish, because figure 8 puffers nip fins.
Sources
- Seriously Fish: Figure Eight Puffer, Tetraodon biocellatus (size, tank size, temperature, pH, hardness, salt, diet and teeth, puffing, tank mates, keeping alone, sexing, breeding). Read October 18, 2026.
- FishBase: Dichotomyctere ocellatus (valid name and synonym, family, freshwater not brackish, 22-26°C, pH 6.5-7.5, dH 5-12, 8 cm TL, aggressive to its own kind, IUCN Data Deficient). Read October 18, 2026.
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