Triggerfish: Characteristics, Behavior, Species

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Picasso triggerfish (lagoon triggerfish, Rhinecanthus aculeatus)

Triggerfish gets their name from their retractable dorsal fin which is usually hidden, but can be pushed out inside a crevice so the triggerfish can lodge itself in safely when pursued by a predator or pushed around by ocean waves. Triggerfish are relatives of blowfish. They use muscles to blow water out of their bodies that are similar to the ones blowfish use to pump in water when they inflate. They are popular aquarium fish and popular among divers and snorkelers.

Many triggerfish are Brightly-colored and have a distinctive, “pouty” mouth. Lines, spots and a numerous of other patterns vary from one fish are a distinguishing characteristics of the Triggerfish family and can be used to tell both species and individuals apart. Tthey are notoriously ill-tempered and aggressiveness, often biting fish and even people many times their size. They have strong jaws which they use to break open molluscs, sea urchins and crustaceans, and can leave behind a nasty bite for unfortunate swimmers.. [Source: Great Barrier]

There are about 40 species in the triggerfish family (Balistidae). They reside in tropical and subtropical oceans throughout the world, with the greatest species variety in the Indo-Pacific region. Most are found in relatively shallow, coastal habitats, especially at coral reefs, but a few, such as the oceanic triggerfish (Canthidermis maculata), are pelagic (live in the open ocean). [Source: Wikipedia]

Many species of the family Balistidae are highly valued as food and frequently caught as bycatch in bottom trawls. They’re considered to be generally good as food Numerous triggerfish species are sought after for the aquarium trade. Triggerfish usually require large aquariums and be aggressive towards other fish. [Source: Animal Diversity Web (ADW), Wikipedia]

Websites and Resources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Fishbase ; Encyclopedia of Life ; Smithsonian Oceans Portal ; Woods Hole Oceanographic Institute ; Cousteau Society ; Monterey Bay Aquarium ; MarineBio

Triggerfish Characteristics and Feeding Behavior

Wedgetail triggerfish (Rhinecanthus rectangulus)

Members of the triigerfish family have a first dorsal spine on the first dorsal fin that can be locked into place, a compressed body with high set eyes, chisel-like teeth and a small mouth placed on a long and tapering snout. There are no pelvic fins. Instead they have a spine-like knob at the end of a long and depressible pelvic bone. The second dorsal and anal fins are comprised of only soft rays. The fish’s rough skin is made up of non-overlapping scales with an area of small tubercles in the center. Their a gill opening are a short slit above and in front of their pectoral fin base. [Source: Emily Nall, Animal Diversity Web (ADW) /=]

Triggerfish move around using fins that are located mostly around the tail. It has a large flapping dorsal fin that its next the tail and an equivalent one on the underside. The trigger, which gives the fish its name, is the leading ray of its dorsal fin. It is bony and hard. The two rays behind it have been turned into a locking device on the joint of its base. When the large trigger spine is erect it remains so until the fish deflexes the smaller second spine, “triggering” the first.

When a triggerfish is threatened or big waves crash over the reef, the fish swims into a crevasse, sticks up its bony trigger and locks into place so firmly that virtually nothing can extract it: ocean currents, predators or scuba divers. Having all of its fins near the rear of its body allows a triggerfish to use its body and mouth to reach choice bits of food.

Triggerfish feed on coral, crushing the stony shells and extracting the polyps. They have sharp teeth and powerful jaws that can crush apart things like crabs, spiny lobsters, burrowing worms, snails and sea urchins. They produce noise when they grate their teeth together.

Triggerfish feed on sea urchins by first blowing a jet of water on the urchin to turn it upside down. Avoiding the short spins on the underside the skilled predator pecks away at the urchin's shell with its beak-like mouth to get at the urchin's fleshy interior. Male triggerfish, fearing competition from the hatchlings of a rival, sometimes lure a female from her nest by feigning an attack just long enough for small predators to feast the her eggs.

Titan Triggerfish

The titan triggerfish (scientific name: (Balistoides viridescens) is also known as the giant triggerfish or moustache triggerfish. With a length of up to 75 centimeters (30 inches), it is the largest species of triggerfish in its range (the stone triggerfish, Pseudobalistes naufragium, from the east Pacific is larger). It is found in lagoons and at reefs up to depths of 50 meters (160 feet) in most of the Pacific Ocean and Indian Ocean but is not found in Hawaii. [Source: Wikipedia]

Titan triggerfish
The titan triggerfish is diurnal (active during the day) and solitary. It feeds on sea urchins, molluscs, crustaceans, tube worms and coral. It often feeds by turning over rocks, stirring up sand and biting off pieces of branching coral. This is why other smaller fish species are often seen around it, as they feed on the detritus and smaller organisms that are stirred up. Titan triggerfish have been observed being aggressive to other fish who enter their territory.

The titan triggerfish is usually wary of divers and snorkelers, but during the reproduction season the female guards its nest, which is placed in a flat sandy area, vigorously against any intruders. The territory around the nest is roughly cone-shaped and divers who accidentally enter it may be attacked. Divers should swim horizontally away from the nest rather than upwards which would only take them further into the territory. Although bites are not venomous, the strong teeth can inflict serious injury that may require medical attention.

The threat posture includes the triggerfish facing the intruder while holding its first dorsal spine erect. It may also roll onto its side, allowing it a better look at the intruder it perceives as threatening its nest. The titan triggerfish will not always bite, but can swim at snorkellers and divers escorting them out of their territory. The flesh of the titan triggerfish is sometimes ciguatoxic.

Orange Striped Triggerfish

Orange striped triggerfish (Scientific name: Balistapus undulatus) are also known as red-lined triggerfish; striped triggerfish, undulate triggerfish and vermiculated triggerfish. They native to western Pacific Ocean and Indian Ocean and can be found as far west as the Red Sea and as far south as Natal in South Africa.[Source: Emily Nall, Animal Diversity Web (ADW) /=]

Orange striped triggerfish are generally found on coral reefs and often in crevices in the reef where they seek protectionby lodging themselves with their first dorsal fin spine. Adults tend to use rock, foliaceous and branching corals while juveniles used turf algae, sand, sponge, and soft corals more frequently. There have not been studies on the life span of orange striped triggerfish specifically but it estimated they have a life span of about 10 years based on studies of other members of the Balistidae family.

Humans utilize orange striped triggerfish for food and in the pet trade. The conservation status of the fish has not been evaluated for International Union for Conservation of Nature (IUCN) Red List: As the orange striped triggerfish is a food fish, it the main predator is humans.Natural predators include a couple of predatory fish species such as bluefin trevally (Caranx melampygusi) and the peacock hind (Cephalopholis argus). Studies have shown that the orange striped triggerfish is a key predator of the sea urchin species, Echinometra mathaei. One study showed that removal of the fish led to increases in the sea urchin population and resulted in negative effects on the coral reef and a decline in the diversity of sea urchin species.

Orange Striped Triggerfish Characteristics and Behavior

orange-lined triggerfish (Balistapus undulatus)

According to Animal Diversity Web: The orange striped triggerfish has a terminal mouth, fully scaled cheeks, and enlarged bony plates behind its gill slit. There is no groove present in front of the eye. The main color of the body is green to brown, and has diagonal curved orange lines as well as narrow stripes of orange and blue going from the mouth to below the pectoral fins The caudal fin is orange-yellow in color, and there is a black area around on the caudal peduncle around the two rows of forward-curved spines. The first dorsal fin is comprised of three spines; the second dorsal has about 26 soft rays, and the anal about 24 soft rays. [Source: Emily Nall, Animal Diversity Web (ADW) /=]

Orange striped triggerfish eat a wide variety of animals from zooplankton to mollusks and are particularly known for eating sea urchin described above. The fish has been observed exhibiting solitary residing behavior, where they stay close to or in the vicinity of their home. They are territorial of their nests, and when frightened will lodge themselves into crevices of the coral reefs using their dorsal spine and pelvic bone. They sense using touch and chemicals usually detected with smell. /=\

The spawning act of the orange striped triggerfish has not been observed but during spawning periods, aggregates of the fish have been observed two to four meters from the sediment. Frequently during spawning times, two to four fish circle each other, occasionally with one nudging at the flank of another using its head, When nesting the fish turns onto one side, flexing its body, and flapping its dorsal and caudal fins. This produces a small hole in the sand in which to lay the eggs. After this one to two fish protect the nest from any predators that might eat the eggs. The eggs are laid in an adhesive mass. They hatch the night of the day they are laid, and embryos are active and free-swimming once they hatch. Based on studies of other triggerfish species, the fish mature at about two years old.

Clown Triggerfish

The clown triggerfish (Scientific name: Balistoides conspicillum) is also known as the bigspotted triggerfish. Because of its coloration, it is highly valued as an aquarium fish. Reaching lengths of up to 50 centimeters (20 inches), the fish has a stocky appearance, oval shape and compressed laterally. The head is large and represents approximately one third of the body length. The mouth is small, terminal and has strong teeth. [Source: Wikipedia]

triggerfish (Balistoides conspicillum)

The clown triggerfish is widely distributed throughout the tropical and subtropical waters of the Indian Ocean and in the western Pacific Ocean. It is most commonly found along external reef slopes with clear water up to 75 meters (245 feet in depth). Juveniles tend to stay below 20 meters sheltered close to caves or overhangs.

The clown triggerfish has a varied of mostly molluscs, echinoderms and crustaceans. It is diurnal generally solitary and defends a territory. It can be very aggressive with other fish and even its own species. The first long dorsal spine when is erected, it is used to impress an opponent or to avoid a predator to pull it out of its refuge.

The first dorsal fin is composed of three spines, one of which is longer and stronger. It is erectile and hidden in a dorsal furrow. This set of dorsal spines composed the trigger system. The second dorsal fin is similar in shape and size to the anal fin which is symmetrically opposed to it. The pelvic fin is reduced to a ventral protrusion.

The background coloration is black. Half of inferior part of the body is marked with big white spots which are more or less round. The area around the first dorsal fin is crossed by yellowish sinuosities which draw like a network reminding the leopard's patterns. There is a yellowish ring around the mouth, which is surrounded by another fin white ring. A white stripe ride the snout just under the eyes level. The second dorsal fin and the anal fin are white and underlined with a yellow line at their base. The caudal peduncle has a yellowish blotch on its top part and has three horizontal sets of spiny scales. The caudal fin is yellowish in its center and has black margin. Juveniles have a black background coloration spangled with small white spots, the extremity of the snout and the base of the first dorsal fin is yellowish.

Gray Triggerfish

The gray triggerfish (scientific name: Balistes capriscus) is also known as the grey triggerfish, leatherjacket, leatherneck and taly. They are found in the western Atlantic Ocean from Nova Scotia south to Argentina, including Bermuda and the Gulf of Mexico. Adults live on hard ocean bottoms, reefs, ledges, and artificial reefs at depths of 24 to 90 meters (80 to 300 feet), either alone or in small groups. Larvae and juveniles drift up to the surface and develop within the planktonic environment (open ocean), and often live among mats of planktonic Sargassum (a floating brown algae) before they move to the bottom.

gray triggerfish (Balistes capriscus)

Adults are primarily olive-gray, have blue spots and lines on the upper body and dorsal (back) fin, and the upper rims of their eyes are blue. Adults have the ability to change color, particularly during the spawning season (April to August). Males turn a dark charcoal gray, while nesting females display a contrasting white and black color pattern.Juveniles are yellowish with small violet dots and can have large, irregular dark patches on the body and fins. Juveniles also have saddle markings and light spots on their dorsal (back) and anal fins.

Triggerfish can grow to be up to six kilograms (13 pounds) and reach a fork length (length from the tip of the snout to the center of the fork of the tail) of 70 centimeters (28 inches) live up 16 years old. Males are larger than females. Adults primarily eat benthic invertebrates including crabs, sea urchins, shrimp, sand dollars, lobsters, and mollusks. They have a small mouth with a strong jaw and specialized teeth used to crush and chisel holes in their hard-shelled prey. Gray triggerfish sometimes direct a stream of water over sandy ocean bottom habitat to expose sand dollars to eat. Juvenile gray triggerfish feed on hydroids, barnacles, and polychaetes. Amberjack, grouper, and sharks prey upon adult gray triggerfish; tuna, dolphinfish, marlin, sailfish, and sharks prey upon juvenile gray triggerfish.

Gray Triggerfish Reproduction

Gray Triggerfish become sexually mature at approximately two years old. Spawning occurs from April to August. Male gray triggerfish establish territories, build nests in the sand, and entice females into the nest to spawn. The male and female tightly circle one another in the nest, rapidly changing color, and the female deposits eggs in the nest shortly afterward.

Females deposit an average of 772,415 eggs. After fertilization females aerate the eggs by fanning and blowing on them. One male can defend up to three active nests on one reef. An active nest is defined as one female on the nest guarding and aerating the eggs. Females also guard the nest from predators, such as wrasses, groupers, and red snappers.

Eggs hatch within 24 to 48 hours and the larvae travel to the surface, where they often live among mats of planktonic (open ocean) Sargassum, a floating brown algae. Larvae and juveniles spend four to seven months in the planktonic environment before they move to the ocean bottom.

Gray Triggerfish Fishing

The gray triggerfish It is caught as a food fish in the U.S. and elsewhere. U.S. wild-caught gray triggerfish is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.Fishing gear used to harvest gray triggerfish has minimal impacts on habitat Regulations are in place to minimize bycatch of sea turtles and smalltooth sawfish that may interact with fishing gear used to harvest gray triggerfish.[Source: NOAA]

There are two stocks of gray triggerfish: the Gulf of Mexico stock and the South Atlantic stock. The Gulf of Mexico stock is not overfished but still rebuilding to target levels (2015 stock assessment), and not subject to overfishing based on 2020 catch data. Scientists conducted an exploratory assessment of South Atlantic gray triggerfish in 2001 and determined that the stock was not subject to overfishing, but overfished status is unknown. A formal stock assessment has not been conducted.

NOAA Fisheries and the South Atlantic and Gulf of Mexico Fishery Management Councils manage the gray triggerfish fishery. Annual catch limits and accountability measures, with automatic triggers to prevent overfishing if the catch limit is exceeded, including shortened future fishing season (recreational) or reduced future catch limits (commercial).Requirements to carry NOAA Fisheries approved sea turtle release gear and follow smalltooth sawfish release protocol to reduce bycatch impacts to protected species. In the Gulf of Mexico, managed under the Reef Fish of the Gulf of Mexico Fishery Management Plan: Recreational and commercial minimum size limits, daily bag limits, and seasonal closures to promote spawning and slow the rate of harvest.

In 2020, commercial landings of gray triggerfish totaled 123,830 kilograms (273,000 pounds) and were valued at approximately $760,000, according to the NOAA Fisheries commercial fishing landings database.Hand lines and electric or hydraulic reels are primarily used to catch gray triggerfish commercially. Recreational harvest is primarily by hook-and-line. In 2020, recreational fishermen harvested 2.4 million pounds of gray triggerfish in the Atlantic and the Gulf of Mexico, according to the NOAA Fisheries recreational fishing landings database.

Image Sources: Wikimedia Commons; YouTube, Animal Diversity Web, NOAA

Text Sources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated March 2023

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