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Blackpatch Triggerfish

Family: Balistidae Picture of a Blackpatch TriggerfishRhinecanthus verrucosus

   The slightly smaller Blackpatch (sometimes incorrectly called Bursa) Triggerfish is easy to mistake for a Picasso Triggerfish, but the big dark oval on the “blackpatch” in their lower back belly is a tell tale sign.   

   The Blackpatch Triggerfish is diamond shaped and flat or laterally compressed like tangs.   The body can be grayish to pale tan, or light brown to yellow, with the exception of white in the chin and chest area around the pelvic spine.  To separate these two colors is a yellow to red pinstripe that curves downward.  There is a dark brown band that runs across the face and downs to their sides that is outlined in bright blue.  That double band can be yellow in the area across the head, over the eyes, but still outlined in blue.  There is a large dark patch that can be black, dark brown or even a dark burgundy, in the lower back half of the body.  Their independently moving eyes are protected by being mounted high on their large head.  They lack a pelvic fin, yet have a pelvic spine.  The first dorsal fin has 3 spines that fold down into a groove in their back or can be locked in an upright position.  Juveniles are a pale tan with the same line to separate the upper and lower colors yet have thinner bars around the eyes.  They still have a darker irregular oval patch near the lower back of their body.  The Blackpatch Triggerfish grows to 9.1” (23cm) and can live up to 6 years.

   Blackpatch Triggerfish are 1 of 8 species in the Rhinecanthus  genus. In comparison, they are said to be one of triggers with the biggest personalities.  Blackpatch’s get their name from that dark patch just over the anal fin area, however it can be a deep burgundy, dark brown to black.  Triggerfish sometimes vocalize a grunting loud enough for divers and aquarists to hear outside the tank.  They also love to rearrange any rock work or items that they are strong enough to move.  They are often confused for a Picasso Triggerfish, however the large black irregular oval in the lower back of the body is a dead giveaway. They are similar in temperament to others in their genus.

   The Blackpatch Triggerfish is moderately easy to care for as long as they are fed enough.  Small specimens can starve if not fed 4 to 5 times a day.  Aside from that, they are fine for beginners.  When cleaning or rearranging the tank, be mindful of their location, since they do inflict a painful bite if they become frightened. They will eat a wide variety of foods that are offered, and are not too picky.  If quarantining, use a large piece of PVC for them to hide in during this period.  Their teeth constantly grow and need hermit crabs and shrimp to wear them down.  Provide a ledge, caves and/or crevice for them to sleep in at night.

   These triggers should be the only one from their genus in the tank.  They can be housed in a community tank only as very small juveniles, however as they age they will turn on their peaceful tank mates.  The best tank mates are larger bolder fish like moray eels, groupers, snappers, surgeonfish, pufferfish, rabbitfish and large angelfish.  The other triggers they can be kept with and only in a much larger tank are the Pinktail Triggerfish (Melichthys vidua), Niger Triggerfish (Odonus niger) and the Scythe Triggerfish (Sufflamen bursa).  Avoid the more aggressive triggerfish like the Queen and Orangelined Triggers since they will attack the Blackpatch.  If setting up a trigger tank, add the most aggressive  last.  They will eat inverts and corals except large stinging anemones like the Heteractis Magnifica and Carpet Anemones.

   Minimum tank size of 125 gallons and 6 feet in length.  When housing with other triggerfish, opt for a tank that is at least 250 gallons.  They are very active and territorial fish, which will do much better in the attitude department if they have enough room.  Provide plenty of brisk filtration, a strong skimmer for good oxygenation, and rock work that is set up as individual islands.  The island set up should also have holes in the middle for them to swim through and hide in, away from each other (if you have other triggers). This will also give them more room to swim, helps divide territory and most importantly will help circulation.

For more Information on keeping this fish see:
Guide to a Happy, Healthy Marine Aquarium

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Tetraodontiformes
  • Family: Balistidae
  • Genus: Rhinecanthus
  • Species: verrucosus
Blackpatch Triggerfish, Bursa Trigger, Rhinecanthus verrucosus

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Blackpatch Triggerfish in captivity

As you watch this elegantly marked Blackpatch or Bursa Triggerfish swim back and forth, it becomes obvious as to why they need a large tank! They are very active and they are easy to keep, however, a tank that is 125 gallons is necessary for this eventually 1 foot long pet fish. These fish are interesting to say the least! They will make grunting sounds and love to rearrange rocks and landscaping in the tank, but need other aggressive tank mates. Provide hard shelled shrimp to wear their teeth down, which continue to grow throughout their lives.

Blackpatch Triggerfish - Quick Aquarium Care
  • Aquarist Experience Level: Beginner
  • Aquarium Hardiness: Moderately hardy
  • Minimum Tank Size: 125 gal (473 L)
  • Size of fish - inches: 9.1 inches (23.11 cm)
  • Temperament: Large Aggressive - Predatory
  • Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
  • Range ph: 8.1-8.4
  • Diet Type: Omnivore
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Habitat: Distribution / Background

   The Blackpatch Triggerfish, Rhinecanthus verrucosus, was first described by Linneaus in 1758.  The name Rhinecanthus is Greek for “nose” (rhinos) and “thorn” (akantha).   Their most common names are Black Patch Triggerfish, Black-Blotch Triggerfish, Black-Tailed Triggerfish, Blackbelly Picassofish, Blackbelly Triggerfish, Blackbar Triggerfish and Bursa Triggerfish.  The names refer to the large black patch on the belly area.

   Blackpatch Triggerfish are found in the Indo-West Pacific from the Chagos Archipelago and throughout Indonesia and then to the Solomon Islands, north to southern Japan and then south to Vanuatu.  They like subtidal reef flats and protected shallow lagoons over rubble in small groups, though they are solitary at times too.  Shy when divers approach, with adults swimming away and juveniles hiding in crevices or holes.  Blackpatch Triggerfish are found from 1 to 66 feet (1 to 20 meters), and similar to others in this genus, the males may patrol a large area with several females and their nests within his boundaries.  Like the Picasso Triggerfish, they may also feed on algae, mollusks such as bivalves and gastropods, detritus, crustaceans such as shrimp, prawns and crabs, urchins, worms, fish, coral, tunicates, sponges, zooplankton, eggs, and forams (Foraminifera).   

   These fish are not on the IUCN Red List for endangered species.

Picasso (Huma) Triggerfish, R. aculeatus:  Similar shape and light yellow base color with lines on the mouth and eyes, but has dark body bars that angle back instead of the black patch at the lower back part of the belly.

Rectangular Triggerfish, R. rectangulus:  Similar colors, however there is a very wide black diagonal bar that runs from the eye to the anal fin and a small black triangle on the caudal fin area.  They also have a white tail.

  • Scientific Name: Rhinecanthus verrucosus
  • Social Grouping: Solitary - Pairs off to spawn.
  • IUCN Red List: NE - Not Evaluated or not listed


   The Blackpatch Triggerfish is football shaped and flat or laterally compressed like tangs.   The Blackpatch Triggerfish is diamond shaped and flat or laterally compressed like tangs.   The body is pale tan to yellow, with the exception of white in the chin and chest area around the pelvic spine.  To divide these two colors is a yellow to red pinstripe that runs from just over the top lip then downward to the bottom of the pectoral fin, which also has this pinstripe at the base.  They have 2 black to dark brown bars that run over forehead and over the eyes, continuing to a point just under each pectoral fin and those bars area also pinstriped in bright blue.  That double band can be yellow in the area on the forehead, between the eyes, but it is still outlined in blue. There is a large dark patch that can be black, dark brown or even a dark burgundy red in the lower back half of the body.  The tail fin has yellow to orange accents on the outer edges and there are 2 pale yellow vertical bars at the back, just after the splotch and then 2 at the base of the tail fin with a black line in the middle on the caudal fin area. Their independently moving eyes are mounted up high on a large head to help protect them against the spines of urchins and spines of lionfish as they pick them apart.  They lack a pelvic fin, yet have a pelvic spine.  The first dorsal fin has one longer spine and 2 shorter ones that fold down into a groove in their back.  This first dorsal fin pops up and locks when they are frightened or startled and they can use it to wedge themselves in the rock if being attacked.  The second dorsal, tail fin and anal fins are clearish tan to pale orange.   Juveniles have more of the white with similar markings that are narrower and/or less colorful.  The Blackpatch Triggerfish is sexually mature around 1.6 years and 5.7” (14.7cm).  Males are larger and will grow to 9.1” (23 cm) and can live up to 6 years.  

  • Size of fish - inches: 9.1 inches (23.11 cm) - Will reach sexual maturity at 5.7” (14.7cm).
  • Lifespan: 6 years - Sexually mature at 1.6 years

Fish Keeping Difficulty

   Blackpatch Triggerfish are moderately easy to keep and are okay for beginners who have an appropriately sized tank and are aware of the aggression of these fish.  The problem arises when a very young juvenile is not fed 4 to 5 times a day and they starve.  To make sure they are getting enough food, watch their back muscles and belly to make sure they are not pinched in, and if they are feed them more often.  When it comes to illness, triggerfish respond well to most treatments and do not seem to suffer as much as other fish if the tank parameters are knocked out of whack.  Some triggerfish are known to jump out of open tanks or spit water out, so a lid may be in order.  Since they are notoriously messy eaters, they benefit from a really good skimmer and some mechanical filtration that will help with organic build up.  Keeping the water clean in this way can help keep them healthy.  At night, Blackpatch Triggers like to sleep on rock ledges near coral heads (use fake if desired) and/or in caves or crevices.  They are known to bite heater tubes and air lines, so one may want to purchase heaters that have protective plastic covers. 

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

   The Blackpatch Triggerfish will eat pretty much anything that moves or doesn’t move!  This non-picky omnivore will accept whatever you want to feed them.  No cheeseburgers, though!  Provide them with a wide variety of meaty marine flesh and marine based veggies. The flesh can be purchased from the grocery store, which tends to be much cheaper than prepared foods.  It an be fresh or frozen then thawed and chopped up.  Feed your Blackpatch Triggerfish shelled foods like hermit crabs, clams and shrimp to wear down their constantly growing teeth.  Flake is okay for juveniles, yet it is not as filling for adults.  Sinking pellets are best so they do not start to associate the surface with food, thus starting to spit water out of the tank at meal time, which may hit some electrical sockets.  A wide variety of foods is key in helping them grow.  If their diet is not adequate, healthy and varied, their coloring will fade. Do not feed foods that are from freshwater, since it is not healthy for them long term.  Feed juveniles 4 to 5 times a day and adults 2 to 3 times per day. 

  • Diet Type: Omnivore
  • Flake Food: Occasionally - Not filling for adults
  • Tablet / Pellet: Yes - Sinking
  • Live foods (fishes, shrimps, worms): Some of Diet - Hermit crabs help to wear down their teeth. Avoid freshwater fish or crabs.
  • Vegetable Food: Some of Diet
  • Meaty Food: Most of Diet
  • Feeding Frequency: Several feedings per day - Feed juveniles 4 to 5 times per day, adults 2 to 3 times per day.

Aquarium Care

   Blackpatch Triggerfish can be housed only with large stinging anemones.  

Reef tanks:
-Medium sized up to 90 gallons, perform 15% bi-weekly. 
-Large Tanks 100 gallons and over, once water is aged and stable can be changed 10% bi-weekly to 20% monthly, depending on bioload.

Fish only tanks:*
-Medium sized up to 90 gallons, perform 20% to 30% monthly depending on bioload. 
-Large Tanks 100 gallons and over, once water is aged and stable can be changed 20% to 30% every 6 weeks depending on bioload.

   For more information on maintaining a saltwater aquarium see: Saltwater Aquarium Basics: Maintenance. A reef tank will require specialized filtration and lighting equipment. Regular water changes done  bi-weekly will help replace the trace elements that the fish and corals use up.  

  • Water Changes: Bi-weekly

Aquarium Setup

   Minimum tank size for the Blackpatch Triggerfish is 125 gallons.  If housing with other triggers of similar size use at least 250 gallons or tank size that is best for larger triggers. They eat a lot of food and are messy eaters, so putting a small baby Blackpatch in a nano tank is unwise since the water will deteriorate quickly.  Live rock situated as individual groupings or islands with openings for them to swim through will help them feel secure.  This also provides a place for them to hide in and these islands help keep the water circulating sufficiently, preventing any dead spots.  At night, Blackpatch Triggers like to sleep on their sides on rock ledges or among coral branches (use fake coral) or in caves or crevices.  This sleeping cave or crevice should become larger as they grow.  They like sand to blow in as they hunt for food and they should have plenty of seashells for them to turn over as they look for prey or to bite into, which will help with their ever growing teeth.   If their teeth are not being properly worn down, they become pointed and long, which can make it hard for them to eat.   Temperatures of 72 to 82˚F with a pH of 8.1 to 8.4 with very strong water movement and good oxygenation by an oversized skimmer is best.   If your trigger starts to shoot water out of the tank to get your attention at feeding time, a lid may be in order.

  • Minimum Tank Size: 125 gal (473 L)
  • Suitable for Nano Tank: No
  • Live Rock Requirement: Typical Plus Hiding Places
  • Substrate Type: Sand
  • Lighting Needs: Any
  • Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
  • Breeding Temperature: - Unknown
  • Specific gravity: 1.023-1.025 SG
  • Range ph: 8.1-8.4
  • Brackish: No
  • Water Movement: Strong - Use an oversized skimmer for good oxygenation
  • Water Region: All

Social Behaviors

   Typical of triggerfish, they are more peaceful as juveniles and grow more aggressive as adults.  Although the Blackpatch Trigger is less aggressive than the Queen or Orangelined Triggerfish, it is still aggressive and tank mates should be carefully chosen.  Triggerfish from this genus cannot be housed together once they are mature.  

   Blackpatch Triggerfish need to have lots of room and lots of food to help with their bad attitude.  They should not be housed with the more aggressive triggerfish like the Queen or Orangelined Triggerfish, however they do well with the Pinktail Triggerfish (Melichthys vidua), Niger Triggerfish (Odonus niger) and the Scythe Triggerfish (Sufflamen bursa).  Aside from these triggerfish, as juveniles they are passive, yet become more aggressive as they age and will start to hunt their “community fish friends” as they age.  They go from, “Fish are not food, they are friends,” to the opposite almost overnight.  The best tank mates are larger bolder fish like moray eels, groupers, snappers, surgeonfish, pufferfish, rabbitfish and large angelfish.  Avoid housing with smaller fish, period.  Groupers should be added right before the trigger as a juvenile and should not be large enough to eat the juvenile triggerfish.  They are known to pick apart Lionfish more so than any genus of triggerfish and love urchins for dinner.

   They will not bother large stinging anemones like the Heteractis Magnifica and the Carpet Anemones, however all other corals are in danger of being eaten or having rocks dropped on them.

   When it comes to inverts, just say no unless you want them to be eaten.

  • Venomous: No
  • Temperament: Large Aggressive - Predatory
  • Compatible with:
    • Same species - conspecifics: No
    • Peaceful fish (gobies, dartfish, assessors, fairy wrasses): Threat
    • Semi-Aggressive (anthias, clownfish, dwarf angels): Threat
    • Aggressive (dottybacks, 6-line & 8-line wrasse, damselfish): Threat
    • Large Semi-Aggressive (tangs, large angels, large wrasses): Monitor
    • Large Aggressive, Predatory (lionfish, groupers, soapfish): Monitor - Avoid lionfish. Groupers should be added as juveniles before the triggerfish so they are not large enough to eat them.

    • Slow Swimmers & Eaters (seahorses, pipefish, mandarins): Threat
    • Anemones: Monitor - Safe with large anemones that have a strong stings.
    • Mushroom Anemones - Corallimorphs: Threat
    • LPS corals: Threat
    • SPS corals: Threat
    • Gorgonians, Sea Fans: Threat
    • Leather Corals: Threat
    • Soft Corals (xenias, tree corals): Threat
    • Star Polyps, Organ Pipe Coral: Threat
    • Zoanthids - Button Polyps, Sea Mats: Threat
    • Sponges, Tunicates: Threat
    • Shrimps, Crabs, Snails: Threat
    • Starfish: Threat
    • Feather Dusters, Bristle Worms, Flatworms: Threat
    • Clams, Scallops, Oysters: Threat
    • Copepods, Amphipods, Mini Brittle Stars: Threat

Sex: Sexual differences

   Males are larger than females at the same age. 

Breeding / Reproduction

   The Blackpatch Triggerfish male, similar to the Picasso Triggerfish will have a large territory he patrols and within that area are several female’s nests.  They will each pair off when it is time to spawn, which is every 3 weeks.  The day before they spawn, the female will dig a pit in the substrate for a nest and then deposit sticky eggs that number in the millions, depending on the size of the mother.  After the male fertilizes the eggs, the eggs are guarded until they hatch into larvae, then they are on their own.  Females guard their eggs and males guard the territory until they hatch.  Once they hatch, they stay in the larval stage for around 100 days.  

  They are not yet bred in captivity, however now that the small foods that larvae need to eat are becoming available, this may change. (March 2015)

  • Ease of Breeding: Unknown

Fish Diseases

   These fish are pretty hardy and will respond to any treatments for any ailment.  They are usually the last to get sick and first to heal.  Triggerfish do not have any known common ailment outside what affects all marine fish.  Feeding young juveniles often is the biggest challenge.


   The Blackpatch Triggerfish is not too hard to find in stores and online.  Online they are about $22.00 USD for a 2” to 3” juvenile. (March, 2015)


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Rhinecanthus verrucosus
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