Marine life identification guide > Pufferfish, porcupinefish & boxfish

Pufferfish, porcupinefish & boxfish species identification guide

You’ll find on this page species belonging to 3 closely related fish families: the Tetraodontidae (pufferfish), the Diodontidae (porcupinefish) and the Ostraciidae (boxfish, trunkfish and cowfish). Both the pufferfish and porcupinefish have the capacity to greatly inflate themselves when threatened, preventing attack by predators. They achieve this by drawing water into a chamber near the stomach.

While the pufferfish have a flexible but prickly skin the porcupinefish have prominent spines, formed from modified scales. The Ostraciidae are encased in a box-like shell of bony plates, with gaps for the eyes, mouth, gills and caudal fin. Within this latter group the cowfish also have small horns.

A fish able to “puff-up” when threatened

Most of the species in these three groups are very easy to identify. They all have a characteristic way of swimming, using their rear-facing dorsal and anal fins, assisted by mid-body, often quite large pectoral fins, particularly in the porcupinefish.  Their eyes are generally large and appear swollen, while their mouth parts project forward and are described as beaklike.  The boxfish have large, highly patterned scales, often hexagonal in form over much of their body.

If the inflated form of the pufferfish and porcupinefish isn’t enough to put you off going near them, then remember that their mouth parts are capable of crushing hard shells of prey species as well as coral. Many of these species are known to bite if handled.

Blackspotted puffer
The blackspotted puffer, which can be light brown, grey, blue-grey or bright yellow, and sometimes grey with a yellow belly, is common on the coral reefs of the Indo-Pacific. Here, encountered in Lagon de la Saline, Réunion Island.

It is also important to note, that many of the species in these three families harbor a powerful toxin, tetradotoxin, which is found in the viscera and gonads.  Some parts of the fugu (species from the Takifugu genus), are considered a delicacy in Japan, but have enough poison to kill around thirty people, if wrongly prepared, in just one fish.  The toxins are also present in the skin of some of the puffer species, particularly the tobies and act as repellants to predators, while boxfish secrete the highly toxic, ostracitoxin when under stress.

Most species grow to 20 to 50cm in length, but the stellate pufferfish (Arothron stellatus) can grow to up to 120cm.  At the other end of the scale the minute juveniles of the trunkfish are worth looking out for.  They are tiny and almost comical in form, often referred to as a pea, they can only maneuver using their fan-shaped pectoral fins.

The pufferfish are a large group with over 800 species, most of which are found in marine tropical and subtropical environments.  The boxfish are more limited with only 144 species, with the porcupinefish comprising 111 species.

Where are pufferfish, porcupinefish and boxfish found?

Pufferfish, porcupinefish and boxfish are easy to spot when snorkeling over coral reefs, rocky seabeds and coral and sand debris, of tropical and subtropical seas, often at very shallow depths. Good places to look are in hollows and underneath ledges, where they are often found sheltering in shaded water.

The white-spotted puffer is common from the Red Sea to the Eastern Pacific, where it abounds on the rocky shores of Costa Rica. The guineafowl puffer, which is sometimes completely yellow, is also widely distributed on the reefs of the Indo-Pacific, for example in the lagoons of Reunion Island.

A snorkeler takes a picture of a yellow boxfish in Maldives
A snorkeler takes a picture of a yellow boxfish at Dhonveli‘s reef flat, Maldives.

If you snorkel in Egypt, Israel, or Jordan, you will certainly encounter the masked pufferfish, endemic to the Red Sea. Whilst pufferfish live mainly in saltwater, some species are also found in brackish water, such as the checkered puffer, commonly spotted at the edge of the mangroves in the Caribbean.

The long-spine porcupinefish and the spotfin porcupinefish are circumtropical, which means that they are present in all tropical seas of the planet. The long-spine porcupinefish has extraordinary gold-flecked eyes, if you are able to get close enough to see them.

In the Caribbean, the spotted trunkfish and the smooth trunkfish are both very common at shallow reefs. In the Indo-Pacific, you will often come across the yellow boxfish, whose miniature juvenile exhibit an adorable bright yellow and black dots coloration.

The whitespotted boxfish, whose male and female have different colorations, is also common at many spots.

Caribbean & Western Atlantic species

Pufferfish, porcupinefish

Boxfish, trunkfish, cowfish

Indian & Pacific Oceans species

Pufferfish, porcupinefish

Boxfish, trunkfish, cowfish

Eastern Pacific Ocean species

Pufferfish, porcupinefish

Boxfish, trunkfish, cowfish

Mediterranean and Eastern Atlantic Ocean species


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