When it comes to oddly shaped sea creatures, the smooth trunkfish, a member of the boxfish family, certainly finds itself in the top ranks.

The smooth trunkfish, otherwise known as Lactophrys triqueter or Rhinesomus triqueter (both names are accepted) is a small tropical and subtropical fish with spectacular coloring and a unique shape.

Together we are going to take a look at the triangular masterpiece that is the smooth trunkfish and learn about this unique creature’s lifestyle.


  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Tetraodontiformes
  • Family: Ostraciidae
  • Genus: Lactophrys
  • Species: L. triqueter/ R. triqueter


The smooth trunkfish is a relatively small tropical fish, reaching an average size of approximately 8 inches (20 cm). However, they can grow much larger and in some cases, reach double that length.

Although they’re members of the box fish family (Ostraciidae), L. triqueter looks much more like a triangle than a box, particularly when viewed from the front.

Their angular body is covered in plate-like scales, which create a bony armor for protection but lacks the spines found on other trunkfish, which gives it a smooth texture, thus resulting in its name.

Smooth trunkfish have a triangular shape when viewed from the front
Smooth trunkfish have a triangular shape when viewed from the front

The color patterns of these fish generally include a dark background, of which the color difference can be in shades of yellow, brown, or gray, and white hexagonal spots.

These spots are often clustered around the center and lateral line of the fish, looking somewhat like a honeycomb.

The eyes, snout, and base of the pectoral fins are dark, with the fins usually appearing yellow.

Juvenile smooth trunkfish are darker in color and have large yellow spots, which eventually fade into the iconic hexagonal markings.

Smooth trunkfish have a small mouth with a pointed snout and protruding lips, looking somewhat like a person pouting.

Habitat and Distribution

Smooth trunkfish are primarily found in the tropical and subtropical waters of the Atlantic Ocean, ranging from as far south as Brazil and spanning through the Caribbean Sea, Gulf of Mexico, Florida, Bermuda, and the Bahamas.

They make their homes in a variety of habitats, including rocky reefs, seagrass beds, and in and among soft and hard coral, and are found mostly in coastal zones.

Smooth trunkfish can be found in rocky reefs, and near the sandy ocean floor
Smooth trunkfish can be found in rocky reefs and near the sandy ocean floor

Within their chosen habitats, smooth trunkfish spend the majority of their time close to the bottom of the ocean, often hovering slightly above sandy sea beds at depths of up to 50 meters.

Diet and Behavior

Smooth trunkfish are extremely agile and, thanks to their pectoral fins, can make quick and precise movements, allowing them to navigate easily through tight spaces and maintain stability while feeding.

When foraging, the fish can be seen blowing jets of water at sediment to uncover hidden food.

Feeding on a variety of benthic animals (bottom dwellers), which include crustaceans, mollusks, worms, and sponges, although the juveniles feed on algae and other plant material.

Smooth Trunkfish are, for the most part, solitary fish and tend to spend the majority of their time alone or in small groups; however, during spawning seasons, they are known to gather in large groups to reproduce.

Reproduction and Life Cycle

Breeding season can vary depending on geographic location and various environmental factors, but when courtship takes place, the male smooth trunkfish will display its colors, and perform movements with its fins, working to attract females.

Females lay their fertilized eggs in the water column where, with the aid of a small oil bubble, they float unprotected from predators.

Juvenile smooth trunkfish are darker than adults and have yellow spots
Juvenile smooth trunkfish are darker than adults and have yellow spots

Within a few days, the eggs will hatch, releasing smooth trunkfish larvae. These larvae are transparent and, similar to jellyfish, are pelagic (meaning they can’t swim and are at the mercy of the ocean currents).

As the larvae mature, they undergo a metamorphosis and develop into juvenile smooth trunkfish. This brings with it the box-like shape and begins to develop colors that are associated with adults.

Over the next few years (the time may vary), the juveniles will reach breeding maturity and continue the cycle.

Predators and Threats

Box fish are small and slow, but due to their shape, they make for an easy catch. 

A variety of sea creatures feed on smooth trunkfish, whether it be opportunistic or a chosen diet.

Fish such as groupers, snappers, barracudas, and reef sharks take advantage of this slow fish when they can, while sea birds such as herons and gulls will grab a trunkfish if the opportunity arises.

Apart from their natural predators, trunkfish face a variety of external threats, mainly due to environmental changes caused by human intervention.

Climate change, destruction of habitats through coastal development and unsustainable recreational activities, and overfishing (particularly as a bycatch) threaten the population of the smooth trunkfish; however, the IUCN Red Listed the fish as “Least Concern“ in 2011 (the last date the population was analyzed).


Are smooth trunkfish suited for human consumption?

Smooth trunkfish are not caught and consumed by humans on a large scale, partly due to their size but more so because of their production of ostracitoxin, which is highly toxic to humans. That said, the fish are caught and carefully prepared in some regions.

Can smooth trunkfish be kept as pets?

Smooth trunkfish, like many marine animals, are not easy to keep in home aquariums. They require very specific water conditions in order to thrive. That said, it is still possible to do so and is often found in large-scale, public aquariums.

How long do smooth trunkfish live?

Smooth trunkfish generally live between 5 and 8 years, with factors such as habitat conditions, predation, and human interaction affecting their lifespan.

Are smooth trunkfish aggressive?

Smooth trunkfish are not generally aggressive towards humans or other fish; however, if threatened, they may become defensive. Although trunkfish won’t cause much harm to a human, they could, if needed, chase other fish from their territory.

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