Rhinecanthus verrucosus (Blackbelly Triggerfish)

Rhinecanthus verrucosus

Last updated on August 17th, 2022 at 05:13 am

Rhinecanthus verrucosus, also known as the Blackbelly triggerfish, is a species of triggerfish belonging to the family Balistidae and native to the Western Pacific Ocean, around southern Japan and Taiwan. It can be found at depths between 3 and 20 meters, inhabiting reef slopes and lagoons, where it can grow up to 23 cm in length. Rhinecanthus verrucosus has no economic value, but it’s often kept in public aquaria.

A medium-sized triggerfish, the Blackbelly Triggerfish (Rhinecanthus verrucosus) has a black-patched belly. This triggerfish is endemic to the Indo-Pacific region but has been found in the Red Sea, Persian Gulf, Indian Ocean, and Western Pacific Ocean as well as Australia and New Zealand.

This marine fish prefers temperate waters ranging from 52 to 86 degrees Fahrenheit (11 to 30 degrees Celsius). In captivity, they can grow up to 9.1 inches (23 centimeters) long.

Together with the hogfish and the tambja family, the blackbelly triggerfish belongs to the family Balistidae and the genus Rhinecanthus. There are 5 species in this genus and 3 of them have been successfully bred in captivity by aquarists (Rhinecanthus aculeatus, Rhinecanthus rectangulus, Rhinecanthus verrucosus). The Blackbelly triggerfish was described by Rafinesque in 1810. Their common names allude to their amazing body structure and coloration.

Origin and description

Rhinecanthus verrucosus

This species is one of over 500 types of triggerfish, a group of fish whose name derives from their ability to trigger spines from their fins as a defense mechanism. The Blackbelly trigger is found in shallow waters off Japan and Korea in temperate waters between 10-12°C.

It is an herbivore that grazes on algae along rocky reefs and seagrass beds with its largemouth. Unlike most other members of its genus, which typically have five rows of teeth in each jaw, Rhinecanthus verrucosus has only four rows; some also have pectoral rays up to 17 rather than 16 as well as differing coloration.

Species profile

Rhinecanthus verrucosus

The Blackbelly triggerfish is a saltwater fish that typically inhabits reefs in Indonesia and Papua New Guinea. It will generally dwell around rubble or coral structures, often on its own or in small groups. This species of triggerfish can reach lengths of up to 14 inches, though most individuals are closer to 15 inches.

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The Blackbelly triggerfish has a maximum lifespan of 7 years. They are not recommended for beginners due to their lots of space requirements in an aquarium and aggressive behaviors during feeding time.

Those planning on keeping them as pets should be sure they have ample knowledge about these fish, as well as tanks big enough for multiple specimens. In captivity, they are known to live alone; however, if kept together they tend to be territorial towards one another until there’s just one left alive.


The Blackbelly triggerfish likes to inhabit shallow lagoon and seaward reefs at depths of 15 to 90 feet. These creatures are most active during daylight hours, especially in the early morning and late afternoon. You can observe these fish from above while snorkeling. They like to make their homes under large coral formations with plenty of nooks and crannies to hide if threatened by a predator. This is where they will lay their eggs when ready for the breeding season.

Rhinecanthus verrucosus size

Rhinecanthus verrucosus can grow to a maximum size of 9.1 inches (23 cm)

Rhinecanthus verrucosus tank size

The minimum recommended tank size is 125 gallons, larger is better, with rocks and caves.

Tank set up

A blackbelly trigger is a very hardy fish, able to adapt to a range of tank environments. It should have plenty of places for it to hide, as well as open areas for swimming and grazing on live rock. Because it is territorial, a single trigger should be kept in a species tank. It will also eat coral, so no soft corals or clams should be present.

The pH should be between 8.1 and 8.4 with a salinity between 1.022 and 1.025, although your pH may vary depending on your water source; check with your local aquarium shop to determine what’s best for you!

Rhinecanthus verrucosus tank mates

Since Rhinecanthus verrucosus is a moderately large triggerfish, you’ll want to make sure you have an equally large aquarium. A 125-gallon tank will give these fish enough room to swim without feeling confined. Some recommended tankmates are other moderately-sized marine fish, like tangs and surgeonfish. They also should be kept with more peaceful tank mates species as they can get pretty territorial!

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This type of trigger has also been known to nip at smaller species if they feel threatened. If keeping more than one in your tank, it is best to add them at separate times so they don’t view each other as competition for food and territory.


Rhinecanthus verrucosus

Blackbelly triggerfish can be bred in a community aquarium with a ratio of one male to two or three females. Because they are semi-aggressive, they are best kept in species only tanks and need plenty of room to grow. Also, remember that all triggerfish eat coral and ornamental algae, so proper tank decoration is a must.

Provide at least 125 gallons for each adult and use rockwork or heavy substrate to give them plenty of hiding places and an area where algae can grow. They are reef safe but may damage stony corals because of their size. If breeding your triggerfish, provide an egg crate on which you will lay your eggs after spawning.

It may take up to 60 days before any fry become free-swimming. After hatching, move your fry into a 30-gallon tank and feed live foods such as newly hatched brine shrimp nauplii.

Maintain stable water parameters, keeping ammonia and nitrite levels zero and nitrates below 20 ppm during rearing stages. Be sure to siphon out excess food from your sand bed daily because these fish like to root around looking for extra food particles—and might stir up too much sand if not monitored closely.

Are Rhinecanthus verrucosus aggressive or peaceful?

Blackbelly triggerfish can be extremely aggressive towards other fish. Care should be taken when keeping them with other docile or peaceful species.

Rhinecanthus verrucosus care

Rhinecanthus verrucosus

Rhinecanthus verrucosus are most commonly found at depths of 10-50 meters (33 to 164 feet). They tend to live in large schools and are often active both day and night, though they may be a bit more active at night. Their diet primarily consists of small invertebrates such as worms, shrimp, crabs, and other fish but can also include sea urchins, octopus, and mollusks.

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The blackbelly triggerfish grows up to 9 inches long and can live for up to 6 years with proper care. It is easy for them to adapt to captivity since their native habitat does not vary much from what is found in home aquariums: sand or sandy/coral substrate, rocks, driftwood, or plants.

What do Rhinecanthus verrucosus eat?

Rhinecanthus verrucosus are herbivores and will eat a variety of marine algae. In captivity, they will eat about any type of algae you put in front of them, but it is best to keep their diet varied by including dried seaweed in their meals once or twice a week. Mixing krill or other meaty foods into their meals is also encouraged. They should be fed 2-3 times per day for maximum health.

Always make sure that all uneaten food is removed from their tank within an hour or two so that leftover food does not rot and create an environment for bacteria to grow. As with most fish, blackbelly triggerfish cannot survive on dead food alone; if you have less than perfect lighting conditions in your aquarium, gut-loaded live food such as Mysis shrimp may need to be introduced into your fishes’ diets at least occasionally.

Water parameters

Rhinecanthus verrucosus

The ideal water pH should be 8.1–8.4, a specific gravity of 1.020–1.025, and a temperature of 72–82°F (22–28°C). The blackbelly trigger likes a slightly alkaline pH with plenty of oxygenated water in a large tank with live rock for shelter and places to hide when stressed or when being fed by hand.

To keep these fish healthy, it is important to keep nitrates under 10 ppm and do not overfeed them. Avoid food that is high in proteins as well as some invertebrates such as clams, lobsters, crabs, etc., which may contain high levels of toxins.

Rhinecanthus verrucosus lifespan

This fish can live up to 6 years in captivity.

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Parasites and diseases

As with most marine fish, Rhinecanthus verrucosus are susceptible to parasites, some of which can be treated with medications. Two common internal parasites in saltwater fish are single-celled protozoans: one causes ich and another is a parasite that causes velvet disease.

Ich is easy to identify as it makes your fish look like they’ve been sprinkled with salt; their skin has white spots all over it. Velvet looks like cotton growing on or under their scales. Your fish might also have external parasites such as copepods or bristlemouths on their bodies or fins, which seem like small strands of thread but can cover up part of a fish’s body if left untreated.


Blackbelly triggerfish have few predators to worry about in their home environment of coral reefs. Large grouper and sea bass will sometimes pick on them, but for the most part, they are safe from predation by other creatures. It is far more likely that blackbelly triggerfish will be preyed upon by humans! These fish are prized for food around Asia; however, overfishing has led many countries to impose restrictions on catching them.

Do Rhinecanthus verrucosus make good pets?

Yes. They are hardy fish that will tolerate any condition, they have a high disease-resistant ability. However, they can become aggressive as they grow up.