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Caresheet: Figure 8 puffer | Tetraodon biocellatus

Last Updated April 4, 2020
tetraodon biocellatus

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Tetraodon biocellatus are commonly known as figure 8 puffers, a name derived from their head markings (which look somewhat like the number eight). Although they are smaller and easier to keep than most  puffer species there are still a lot of misconceptions out there about these fish. They are not freshwater fish nor are they suitable for community aquariums, but don’t let this stop you from keeping them!

Keep reading for everything you need to know about keeping figure eight puffer fish.

Note: figure 8 puffers belong in brackish tanks. If you’re looking for a freshwater puffer, try having a look at this list.

Minimum tank size20 gal (75 L) long
TemperamentVery aggressive
Temperature73.5-79 °F/21-26 °C


Tetraodon biocellatus, figure 8 puffer, figure eight puffer, eyespot puffer

Figure 8 puffer natural habitat

Figure 8 puffers are naturally found in estuaries, mangrove forests and streams in Southeast Asia, where they inhabit calm waters.

Figure 8 puffer appearance

With a maximum size of around 4 inches (10 cm), figure 8 puffers stay relatively small. Their appearance is quite striking, with a creamy white belly, yellow body and black markings. As mentioned in the intro, their common name is derived from the “eight”-shaped marking on their head.

Figure eights are sometimes confused with young Ceylon puffers (Tetraodon fluviatilis) or green spotted puffers (Tetraodon nigroviridis), so if you’re planning on keeping one be sure to double check whether you’re buying the right fish!

Figure 8 puffer requirements

Although they’re one of the easier puffer species, figure 8 puffers (and most others except for the tiny dwarf puffer) are not a great choice for beginning aquarists as they require relatively specific care. For a single figure 8 puffer, an aquarium of at least 20 gallons (75L) with heavy filtration is recommended as they produce a lot of waste and are messy eaters.

Although many sites list figure 8 puffers as a freshwater species, these fish will do much better in a low-end brackish aquarium with a salinity of at least around 1.005. Setting up a brackish aquarium can sound intimidating but is actually very similar to starting a freshwater tank: all you need to get started is a proper refractometer and some marine aquarium salt.

Like all puffers, figure eights are very easily bored and require a densely planted, well-decorated tank. A bored puffer will spend much of its time “glass-surfing”, swimming up and down the front of the tank. Finding plants that can withstand brackish water might seem challenging but luckily some of the easiest plants in the hobby (like Java fern) can actually withstand a relatively high salt grade and will do fine. You can also add plenty of driftwood and rocks to keep your puffer occupied.

Note: if you’re not sure how to set up a brackish aquarium have a look at this article, which contains everything you need to know.

Anthony the figure 8 puffer fish

Figure 8 puffer tankmates

Like all puffers, figure eights are very aggressive and the easiest way to keep them is a single-species setup with a single specimen. This prevents any possible trouble with tankmates being nipped at, damaged or even eaten whole.

If you do want to keep your figure 8 puffer with other fish there are a few options, although you’ll always have to have a plan B in case things do go south. In large enough aquariums figure 8 puffers can sometimes be kept in groups. You might also be able to succesfully keep them with bumblebee gobies (Brachygobius sp.) and other quick, short-finned fish that tolerate a similar salt grade and temperature.

Figure 8 puffer diet

Their diet is one of the most challenging aspect of keeping any puffer and this is no different for figure eights. Pellet and flake foods are not suitable (nor will they be accepted by most puffers). Almost all puffers have teeth that are adapted to hard and crunchy foods and will continue to grow their entire lives to deal with this type of diet. This means that if you don’t offer enough of these foods your puffer’s teeth will eventually overgrow, rendering it unable to eat and resulting in you having to clip them by hand; obviously not a pleasant experience for the puffer in question.

Thus, to keep puffer teeth short their diet should consist mostly of crustaceans, possibly supplemented with other live or frozen foods like mosquito larvae and bloodworms. Live foods are a great option: you can breed snails, dwarf shrimp and dwarf crayfish yourself at home. You can also use store-bought frozen mussels, crab legs, clams or shrimp soaked in a vitamin supplement.

Juvenile puffers can be fed daily, adult fish only need a meal every few days. Figure eight puffers are very messy and noisy eaters that are fun to watch! Once they get a snail shell in their mouth, all you’ll hear is them loudly crunching away, only to spit out the shell once they’re finished.

Note: Malaysian trumpet snails are not a suitable puffer food as their shells are too hard and can cause tooth damage.

Figure 8 puffer behavior

So why keep figure 8 puffers if they’re such a challenge? Their behavior more than makes up for it. These are one of the most intelligent fish species to be found in the aquarium store: they always seem to be observing their environment, know when it’s feeding time and can even learn to differentiate between their owner and other people after a while.

The figure 8 puffer fish can also puff up to two or three times its original size by inflating its stomach with air or water, which is always neat to see. Puffers typically do this when threatened, although they’ve been seen puffing up in home aquariums for seemingly no reason as well. Perhaps this is another way of dealing with boredom, similar to glass-surfing?

Few things are more amusing than a puffer “helicoptering” in front of an object to closely inspect it (and then possibly eat it)!

Breeding figure 8 puffer

There have been no reports of figure 8 puffers being bred in captivity so far. There’s word that the female may lay eggs along flat surfaces or substrate while the male watches over for a week or so.

Buying figure 8 puffer

Since captive-bred figure eight puffers are not readily available, be aware that any you purchase are likely wild-caught. There’s heated debate surrounding purchasing wild-caught fish, so it’s best to do your research beforehand to learn where you personally stand on the issue.

When getting a new figure eight puffer, be sure to quarantine it since wild populations may carry internal parasites or other illnesses. Some internal illnesses can be hard to treat since puffers don’t readily take medicated dead food. Some hobbyists try to mix the food with a touch of garlic to entice the fish and others put the medicated food on thread to replicate the movements of live food.

If you have any more questions about keeping figure 8 puffers (Tetraodon biocellatus) or if you want to share your own experiences with this interesting and intelligent fish species, don’t hesitate to leave a comment below!

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  • Reply Patti Kelnhofer July 26, 2020 at 3:07 pm

    Hello Mari, I’m doing my homework on figure 8 puffers. I just bought a 37 gallon aquarium. It’s 30in L X 12.4in W X 22in H.
    Will this be fine for a figure8?
    I went to a Asian grocery store and for frozen food it was all cooked. Will that be all right to feed figure 8?
    Thank you, Patti.

    • Reply Jennifer Doll July 26, 2020 at 4:11 pm

      Hi Patti!
      Yes, a 37 gallon is a great start. You could probably even add one more comfortably without any problems.
      It is not recommended to feed cooked food to your puffer. Cooking food reduces some of the natural nutrient contents that come in raw foods; some hobbyists have even said that cooked food is harder for your fish to digest.
      It is especially important to not cook the food if you’re buying crustaceans/mollusks. You want your puffer to have to chomp on hard shells so that it files away at their teeth.
      Hope this helps!

  • Reply Kiana Kelley February 9, 2020 at 7:49 pm

    Hello, I love your article. I have been wanting a figure eight puffer for a very long time and have done a lot of research on these great guys. I currently own a 37 gallon tank with a dragon gony, four black Molly’s, and a few bumblebee gobies. I have a ten gallon set aside to raise food for my puffer, but first to quarantine them. My concern is, I cannot seem to find information on what medications I should be treating my F8 with or what recommended filter to use. I know F8’s are very messy fish and I want to provide a great home for him. Right now I’m using a large LED squeak filter that came with the set of my tank. It seems to do a great job and has a strong filter flow which I know would entertain him, but I’m concerned if it will keep up with his messy eating habits. Any recommendations?

    • Reply Jennifer Doll March 6, 2020 at 9:42 pm

      Hi Kiana,

      Great job doing research! Depending on what you’re treating for, I would recommend the brands: PraziPro or Metroplex. As for filters, the bigger you can go without creating too much flow is best. Most people go with filters that are double of what is recommended for the tank size. If you can give more specifics, I can help better!

      Good luck and happy pufferfish keeping!

  • Reply Rik Herman August 8, 2019 at 10:34 pm


    I have a 15 gallon tank. One 8-fig puffer for almost 3 years but i have a big problem. He is glass surfing most the time and that is only when me or someone else comes close to the aquarium. He also jump out of the water if i come to close to the tank. I test my water regularly and everthing is fine, also there is enough decoration for him. So i really dont know what i need to do. Can you please help me?
    Kind regards Herman

    • Reply Mari August 10, 2019 at 10:56 am


      Sorry to hear you’re worried about your puffer. Some degree of glass surfing is impossible to avoid I guess, my two Amazon puffers do the same thing. However, if you feel like it’s a constant thing then we’ll have to think of something to distract him a bit. 15 gallons is a little on the small side in my opinion for an F8 but since the minimum I recommend is only 5 gallons more I don’t think you’d be motivated to upgrade him.

      Here are some things that have worked for me. We have large cherry shrimp colonies in our other aquariums, so sometimes I release a bunch for them to hunt down, which is challenging since there are so many hides and keeps them occupied. They also love surfing in the strong filter flow. My tank has lots of nooks and crannies for them to swim through and hunt in, which they tend to do since they know that there’s stuff to find there sometimes. Heck, you can even make them chase a laser light like a cat!

      I hope that helps 🙂

  • Reply Jord July 30, 2019 at 12:19 am


    I am planning on establishing a aquarium to get a figure 8 puffer. I’ve done alot of research and know what my I need to buy to make the ideal aquarium for my puffer.

    Right now I’ve come to the fun part where I can decorate my aquarium. I am planning on putting a fake crocodile skull in there with the java plants you suggested. But I was wondering if there’s a ideal type of sand or stone for him te hide in. Maybe something that keeps the pH level stady or something like that.

    What would you recommend?

    Thank you in advance.

    • Reply Mari July 30, 2019 at 12:46 pm

      Hey! That sounds like such a fun project 🙂

      For hiding spots you can try looking into cichlid stones or caves, they make the perfect place for any fish to retreat to. As for substrate, you don’t necessarily need something special, so it all depends on the look you’d like to go for with your tank. You can use aragonite or crushed coral to keep the hardness high if you’re worried about it, though.

      Good luck, sounds like everything should end up going just fine for you!

  • Reply Samantha June 29, 2019 at 3:52 am

    I have a 5 gallon tank with two figure 8 puffers. The water is not salted at all and there is two fake plants. I will feed them snails twice a month and frozen bloodworms every day. One kind of bullies the other. Is all of this okay? I really need help.

    • Reply Mari June 30, 2019 at 10:16 pm


      As you can read in this article, unfortunately your set-up is not suitable for figure 8 puffers at all. If you want to fix this so they can live a long and happy life, you’ll need to start adjusting things ASAP to match the guidelines mentioned. The minimum tank size for a figure 8 puffer is a 20 gallon long and they cannot be kept in pairs as you’ve mentioned, unless you happen to have a very large aquarium to offer. The water should be low-end brackish, there’s a link to an article describing how to in the caresheet. As for diet, they really need more molluscs.

      Judging from all this it seems like you might not have been prepared for all this. Is there any way you can return the fish to the store? It’ll be a long and expensive ordeal to upgrade them to where they can truly thrive.

      Sorry I don’t have better news! Hope things end up okay with them.

  • Reply Chris Takagi February 7, 2017 at 12:38 pm

    Hi, I’ve seen in some places that you can keep these with Bumblebee gobies, is that true, and if so, how many gobies & puffers could I keep in a 120cm long, 45cm deep 55cm tall tank?

    • Reply Mari February 8, 2017 at 6:28 pm

      Hi! I’ve seen this done and recommended in some places as well. I agree it’s probably possible to keep them together though you should always have a plan B for the gobies in case your puffer turns out to be a cold blooded killer. It’s also not 100% the most ideal situation; bumblebee gobies do best in a single-species setup.

      As for the amount of fish, I wouldn’t go for more than one puffer – not worth the risk, in my opinion. You could keep quite a few gobies, though, they are very small. If you haven’t seen it yet be sure to have a look at the new bumblebee goby caresheet here. 🙂

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