Figure 8: Species Profile of Puffer Fish

Tetraodon biocellatus Figure 8 Puffer Fish

Few people can resist seeing a pufferfish, and the little figure 8 puffer could be one you'd like to bring home to your own freshwater tank. Their appealing features include expressive expressions, intellectual curiosity, and propeller-like fins. The capacity of pufferfish to inflate themselves with water or air when frightened gives them their name. This is a very effective defense mechanism since swallowing a growing fish is more difficult!

Species Overview

Common Names: Figure 8 puffer, eyespot pufferfish

Scientific Name: Tetraodon biocellatus

Adult Size: Up to 2 1/2 inches (6 cm)

Life Expectancy: 5 years


Family Tetraodotidae
Origin Freshwaters of Southeast Asia
Social Aggressive
Tank Level Mid to Lower
Minimum Tank Size 15 gallons
Diet Live foods, prefer snails and shellfish
Breeding Egglayer
Care Intermediate
pH 7.0 to 7.5
Hardness 5 to 12 dGH
Temperature 72 to 79 F (22 to 26 C)

​​Origin and Distribution

The figure 8 puffer is found in Southeast Asia's brackish (partially salinized) streams and estuaries, including Borneo, the Malaysian peninsula, Sumatra, and Thailand. Despite the fact that these fish do not reproduce in captivity, they have not been overfished for the trade and are not classified an endangered species. Figure 8 puffers in home aquariums were all collected in the wild, which means they must be quarantined when they initially arrive. Ascertain that young puffers do not infect other fish.

Colors and Markings

Figure 8 puffers are little pufferfish, reaching an adult size of less than three inches. On the upper half of their bodies, they are dark brown, with white on the underside. Yellow dots and lines can be found all over the body. The name comes from the fish's patterns on the back, which approximate the shape of a figure eight.

All figure 8 puffers have a roly-poly look even when not frightened; a well-fed puffer may be identified by its rounded belly. Puffers have two sets of teeth that are fused together to give it a beak-like look. Its peculiar tooth arrangement allows it to smash hard materials like crustacean shells. The teeth of the fish develop throughout their lives and must be ground down to prevent them from becoming too long. As a result, they require hard-shelled meals to maintain the right length of their teeth.


Puffers are not suitable for a community tank because to their aggressive nature. Figure 8 puffers should ideally be maintained alone or in a big aquarium with only a few other fish that flourish in a similar partial-salinity environment. Bumblebee gobies, knight gobies, and mollies are good companions for those who keep them in brackish water. Fish such as barbs, "sharks," and tetras have been known to be kept alongside them in freshwater aquariums. As a general rule, you won't be able to keep them in a regular freshwater community tank.


Even puffers that have previously been docile and tolerant can become aggressive as they age, and if they are insufficiently fed. A puffer can turn on its tankmates and chew them to pieces.

Figure 8 Puffer Habitat and Care

There is debate about whether any puffers are real freshwater fish. They are native to Southeast Asia's freshwater, and while they can withstand brackish or even complete saltwater, they may do best in freshwater. Others have claimed that salinity in the region of 1.005 to 1.008 will dramatically increase the longevity of the figure 8 puffer. Comparative lifespans in captivity when confined in varied salinities are sparse in scientific evidence.

Figure 8 puffers produce a lot of trash while they feed, therefore filtration should be strong. They are sensitive to ammonia, nitrites, and nitrates, and will not thrive in a tank that is currently establishing itself. This fish requires frequent water changes to preserve clean aquatic conditions.

Figure 8 puffers, unlike other fish, can identify and respond to their owners, yet they may also get bored and listless. As a result, they need plenty of open room to swim, as well as places to hide and investigate. They may be harsh on plants since they attack their food vigorously; food fragments shower down on plants and other aquarium décor. Decorate the tank with strong plants, and keep in mind that you may need to replace them at times.

Figure 8 Puffer Diet and Feeding

One of the more difficult components of keeping figure 8 puffers is their feeding requirements. In the wild, they consume crabs and mollusks. Their nutritional requirements are not met by flakes or dry meals. Clams, crayfish, crickets, daphnia, krill, oysters, plankton, scallops, snails, shrimp, and worms are among the meaty and hard-shelled things they must consume.

Because the figure 8 puffer's nutcracker-like beak can become overgrown, it's necessary to feed them enough of hard-shelled items to keep the teeth ground down. Tetraodon snails, often known as pond snails, are ideal for this. While live meals are preferred, some owners have had success training their puffers to eat frozen items. Make careful you get frozen items of good quality.

Gender Differences

Even for professionals, sexing out figure 8 puffers is virtually impossible. The most reliable method of sexing them is to see the female deposit eggs, which is a very unusual occurrence. There have only been a few reports of spawning in captivity.

Breeding the Figure 8 Puffer

The best way to breed figure 8 puffers is unknown. They are said to have placed eggs on a flat surface, such as the substrate, on the rare times that they have spawned in captivity. The male guards the eggs for about a week, until the fry are able to swim freely.

More Pet Fish Species and Further Research

If you’re interested in a similar species, check out this other brackish water puffer:

Check out additional fish species profiles for more information on other freshwater fish.