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Porcupine Puffer | Caring for Diodon holocanthus

If there ever was an aquarium fish that could be labeled as ‘endearing’, it has to be Diodon holocanthus. Also known as the porcupine puffer (or blowfish, in non-aquarist circles), this funny-looking species is appreciated for its strange appearance and big personality.

Keep reading for everything you need to know about porcupine pufferfish care and keeping this species in your marine aquarium!

Name (Common, Scientific)Porcupine puffer fish, long-spine porcupinefish, blowfish, balloonfish, Diodon holocanthus
Minimum tank size200 gallons
Minimum group size1
Temperature75-82 °F
Salinity1.020-1.025
pH8.1-8.4
Difficulty levelHard

Porcupine puffer description & natural habitat

Description

Of course, their looks are what this species is famous for. A relaxed porcupine puffer is shaped like an elongated, skinny oval, with spikes lying flat all over its body. Its strong, beak-like teeth cause a sort of permanent, awkward smile. Brownish in color with black spots, the species is also sometimes referred to as the freckled porcupinefish (or long-spine porcupinefish).

The real magic happens when a porcupine puffer is agitated. Like many species in the order Tetraodontiformes, they possess the ability to swallow large amounts of water, causing them to puff up to a huge size. The difference is that the porcupine puffer, unlike the closely related but smooth-skinned pufferfish, has spikes. These stand straight up when the fish inflates, making for a pretty menacing display!

The porcupine puffer is not a small fish. They can reach a size of 20”, which is why they’re only suitable for experienced aquarists with a lot of room to spare.

The species is easy to recognize while diving thanks to its large size and slow swimming style, with the dorsal and anal fins furiously waving from side to side when it tries to speed up. This unusual way of moving gives the fish exceptional stability and maneuverability.

Did you know? Porcupinefish are not true pufferfish (family Tetraodontidae). Rather, they belong to the family Diodontidae. You can read more about the differences between the two in the article about pufferfish vs blowfish.

Habitat

Porcupine puffers have a very wide natural range. They’re what is called a “circumtropical” species, which means that they can be found in tropical waters all around the world. In fact, sometimes they even stray out of the tropical zone and pop up in the subtropical waters of places like New Jersey, USA, or the Tasman Sea.

In its natural habitat, the long-spine porcupinefish can be found mostly on and around the reef. Although it has been spotted in waters up to 650 ft in depth, it usually doesn’t go much deeper than 115 ft.

Although porcupine puffers are generally solitary beings, younger fish may form small groups.

Vintage illustration of Diodon holocanthus, the long-spined porcupinefish.

Porcupine puffer aquarium

As mentioned above, the porcupine puffer fish is not among the smaller marine species. One of the reasons it’s considered difficult to keep is the sheer tank size necessary to keep one happy and healthy. Some sources consider 100 gallons adequate, but we personally lean more towards a 200-gallon minimum for this puffer.

The reason for this recommended aquarium volume is not just the porcupine puffer’s size. Like other puffers, they’re also extremely messy eaters that tend to scatter food bits all over the aquarium and produce a lot of waste. In a smaller set-up, water quality can quickly plummet.

Aside from a large aquarium, you’ll also need a powerful filtration system, and it’s very important to keep up with regular water changes and other aquarium maintenance. Provide plenty of hiding places, but be sure to also leave your porcupine puffer some room to swim.

Tip: You should never expose your porcupine puffer fish to air. Their stress reaction of puffing up can cause them to ingest air, which is then almost impossible to expel.

Longspined porcupinefish underwater photo

Porcupine puffer compatibility

Choosing tankmates for a porcupine puffer fish is not the easiest task. Smaller species can be considered food, while anything slow-moving or possessing long, flowy fins presents a fun opportunity for nipping at.

Larger, aggressive species won’t be appreciated either: they can really stress your porcupine puffer out. Tangs and wrasses tend to be considered alright choices, but really, these funky fish shine most when they’re kept alone.

You can keep your porcupine puffer with more members of its own species, as they do occur in groups, especially when they’re younger. It’s not an easy feat, though, considering the species’ waste output—and they may not want to live together anymore once they get older.

As for reefs, you might want to forget about that. This porcupinefish has evolved specifically to eat invertebrates. Although most studies didn’t find corals in their stomachs, they’re likely to damage them anyway while hunting and with their clumsy swimming style.

Porcupine puffer diet

Before considering a porcupine puffer fish as a pet, you’ll have to think about whether you’re willing and able to deal with the diet they require. A bit like rabbits, the fused teeth of a porcupinefish never stop growing. This comes in handy if you live off molluscs and other invertebrates whose hard shells can easily wear down your chompers!

Judging from their stomach contents, wild porcupine puffers keep their teeth in good condition with ease thanks to their crunchy diet of limpets, bivalves, (hermit) crabs, conchs, urchins, and even starfish.

In the aquarium, puffer teeth pose a problem. You have to feed your porcupine puffer fish a diet consisting (almost) completely of hard foods like in-shell mussels, clams, crab and the like. If you don’t, your fish will eventually be unable to eat due to overgrown teeth.

It’s possible to cut or file down porcupinefish teeth, but of course, prevention is better than cure. The process can be very stressful to your fish and if something goes wrong, might even turn out fatal.

Diodon holocanthus or porcupine puffer fish close-up

Breeding porcupine puffers

Sorry, not much luck here! The amount of space it would require to breed porcupine puffers, as well as their complex mating rituals, mean that it has never really been done. Not much is known about how they breed, although a 2015 study does suggest they reproduced in the Japanese Shimonoseki Marine Science Museum Aquarium at least once.

Here’s what scientists have been able to conclude about their reproduction so far:

  • According to a 1997 study, porcupine puffers likely spawn during spring tide (full moon) and the days after.
  • When they breed likely depends on their location. According to a 2011 study, on the Central Pacific Mexican coast, reproduction happened in June and between September-December.
  • Like many other marine fish, porcupine puffers start out their lives as tiny larvae, which makes them difficult to raise. According to a 1978 publication, the eggs and larvae are pelagic (occurring in open water, rather than near the shore).

Conclusion

The porcupine puffer fish is an incredibly fun fish to keep. It can learn to recognize its owner and will enthusiastically respond to your presence. The species even sometimes blows water out of the tank during feeding time!

This being said, this is not a fish for beginning aquarists. Not sure you have what it takes? We can help. FantaSEA Aquariums can design, build and maintain your fish tank for you so all you have to do is enjoy it. Contact us for more information.

Sources & further reading

Brainerd, E. L. (1994). Pufferfish inflation: functional morphology of postcranial structures in Diodon holocanthus (Tetraodontiformes). Journal of morphology, 220(3), 243-261.

DiSalvo, L. H., Randall, J. E., & Cea, A. (2007). Stomach contents and feeding observations of some Easter Island fishes. Atoll Research Bulletin.

Doi, H., Sonoyama, T., Yamanouchi, Y., Tamai, K., Sakai, H., & Ishibashi, T. (2015). Adhesive demersal eggs spawned by two southern Australian porcupine puffers. Aquaculture Science, 63(3), 357-359.

Fujita, T., Hamaura, W., Takemura, A., & Takano, K. (1997). Histological observations of annual reproductive cycle and tidal spawning rhythm in the female porcupine fish Diodon holocanthus. Fisheries science, 63(5), 715-720.

Kuiter, R.H. and Tonozuka, T. 2001. Pictorial guide to Indonesian reef fishes. Part 3. Jawfishes – Sunfishes, Opistognathidae – Molidae. Zoonetics, Australia.

Leis, J. M. (1978). Systematics and zoogeography of the porcupinefishes (Diodon, Diodontidae, Tetraodontiformes), with comments on egg and larval development. Fish. Bull, 76(3), 535-567.

Wiktorowicz, A. M., Lauritzen, D. V., & Gordon, M. S. (2010). Powered control mechanisms contributing to dynamically stable swimming in porcupine puffers (Teleostei: Diodon holocanthus). Animal locomotion, 87-97.

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Marijke Puts

Hey! I'm Marijke, FantaSEA's resident blog writer. I'm a full-time pop science author, part-time PADI diver and snorkeler, and have been keeping fish since I was a kid. When I'm not writing fish care guides, you can usually find me underwater or trying to figure out how to fit more tanks into my house.

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