Common names

Types of triggerfish

8 species carry triggerfish in an English common name. They sit in 1 family, so the group is a name, not a scientific rank.

About triggerfish

Triggerfish are one of 41 species of marine, ray-finned fishes belonging to the family Balistidae. Often brightly colored and marked by lines and spots, they inhabit tropical and subtropical oceans throughout the world, with the greatest species richness in the Indo-Pacific. Most are found in relatively shallow, coastal habitats, especially at coral reefs, but a few, such as the oceanic triggerfish (Canthidermis maculata), are pelagic, inhabiting the open ocean.

Fish of this family are sometimes eaten by humans. While several triggerfish species are popular in the marine aquarium trade, they are often notoriously ill-tempered.

Description

Triggerfish have an oval-shaped, highly compressed body. The head is large, terminating in a small but strong-jawed mouth with teeth adapted for crushing shells (durophagy). Each jaw contains a row of four teeth on either side, while the upper jaw contains an additional set of six plate-like pharyngeal teeth. The eyes are small and set far back from the mouth, towards the top of the head. The gill plates (opercula), although present, are also not visible; they are overlaid by tough skin covered with rough, rhomboid scales that form a stout armor on their bodies. The only gill opening is a vertical slit, directly above the pectoral fins. Their small, restricted gill openings are a trait shared with other Tetraodontiformes.

The anterior dorsal fin is reduced to a set of three spines, with the first spine is stout and by far the longest. All three are normally retracted into a groove. As a protection against predators, triggerfish can erect the first two dorsal spines; the first (anterior) spine is locked in place by erection of the short second spine, and can be unlocked only by depressing the second, "trigger" spine, hence the family name "triggerfish". This locking mechanism allows these fish to anchor themselves within crevices.

Characteristic of the order Tetraodontiformes, the anal and posterior dorsal fins are capable of undulating from side to side to provide slow movement and comprise their primary mode of propulsion, using a method called balistiform locomotion. The sickle -shaped caudal fin is used for faster swimming, such as when evading predators. The two pelvic fins are overlaid by skin for most of their length and fused to form a single spine, terminated by very short rays, their only external evidence.

With the exception of a few species from the genus Xanthichthys, the sexes of all species in this family are similar in appearance, with little sexual dimorphism.

The largest member of the family, the stone triggerfish (Pseudobalistes naufragium), reaches 1 m (3.3 ft), but most species have a maximum length between 20 and 50 cm (8–20 in). Triggerfish appear to have grown to even larger sizes in prehistory, with the extinct Balistes crassidens and Balistes vegai, both fossil species from the Miocene of the Caribbean, potentially reaching up to 1.8 metres (5.9 ft), making them the largest triggerfishes known to have ever existed.

Nomenclature

The triggerfish family, Balistidae, was first proposed in 1810 by French polymath Constantine Samuel Rafinesque. The closest relatives to the triggerfishes are the filefishes belonging to the family Monacanthidae, and these two families are sometimes classified together in the suborder Balistoidei, for example in the 5th edition of Fishes of the World. Other authorities, however, also include the families Aracanidae and Ostraciidae within the suborder Balistoidei.

Etymology

The triggerfish family has both a common name and a scientific name that refers to the first spine of the dorsal fin being locked in place by the erection of the shorter second trigger spine, and unlocked by depressing the second spine. The type genus Balistes is taken directly from their Italian name pesce balestra, the "crossbow fish"; this references the ballista, a siege engine resembling an oversized crossbow which possesses a trigger mechanism.

Genera and species

The following cladogram is based on a 2016 molecular study of filefish and triggerfish (Balistoidea):

Behavior

The anatomy of the triggerfish reflects its typical diet of slow-moving, bottom-dwelling crustaceans, mollusks, sea urchins, and other echinoderms, generally creatures with protective shells and spines. Many also take small fishes and some feed on algae, such as the members of the genus Melichthys. A few, for example the redtoothed triggerfish (Odonus niger), mainly feed on plankton. They are known to exhibit a high level of intelligence for a fish, and have the ability to learn from previous experiences.

Off Florida, juveniles of some species of triggerfishes are found in floating Sargassum, where they feed on the small shrimp, crabs, and mollusks found there.

Reproduction

Triggerfish spawning is timed in relation to lunar cycles, tides, and time of changeover of tides. In relation to lunar cycles, eggs are observed 2–6 days before the full moon and 3–5 days before the new moon. In relation to tides, spawning happens 1–5 days before the spring tide. In relation to timing of tides, eggs are observed on days when high tides take place around sunset.

Triggerfish males migrate to their traditional spawning sites prior to mating and establish territories. Males of certain species (i.e. Balistes carolinensis and Pseudobalistes flavimarginatus) build hollow nests within their territories. Male and female triggerfish perform certain prespawning behaviors - blowing and touching. Pairs may blow water on the sandy bottom (usually in the same spot at the same time) and set up their egg site. They touch their abdomens on the bottom as if they are spawning. During actual spawning, eggs are laid on the sandy sea bottom (triggerfish are demersal spawners despite their large size). Eggs are scattered and attached to sand particles. Triggerfish eggs are usually very small (diameter of 0.5–0.6 mm) and are easily spread by waves.

Territoriality

Triggerfish males are fierce in guarding their territories as having a territory is essential for reproduction. A male's territory is used for spawning and parental care. Most male territories are located over a sandy sea bottom or on a rocky reef. A single territory usually includes more than one female, and the male mates with all of the females residing in or visiting his territory (polygyny). In Hachijojima, Izu Islands, Japan, one male crosshatch triggerfish (Xanthichthys mento) has up to three females in his territory at the same time, and mates with them in pairs. Each male red-toothed triggerfish (Odonus niger) mates with more than 10 females in his territory on the same day. Yellow margin triggerfish (Pseudobalistes flavimarginatus) also exhibit polygyny.

Some triggerfish species can be quite aggressive when guarding their eggs. Both the Picasso (Rhinecanthus aculeatus) and titan triggerfish (Balistoides viridescens) viciously defend their nests against intruders, including scuba divers and snorkelers. Their territory extends in a cone from the nest toward the surface, so swimming upwards can put a diver further into the fishes' territory; a horizontal swim away from the nest site is best when confronted by an angry triggerfish. Unlike the relatively small Picasso triggerfish, the titan triggerfish poses a serious threat to inattentive divers due to its large size and powerful teeth.

After spawning, both the male and female participate in caring for the fertilized eggs (biparental egg care). A female triggerfish stays near the spawning ground, around 5 m off the bottom, and guards the eggs within her territory against intruders. Some common intruders include Parupeneus multifasciatus, Zanclus cornutus, Prionurus scalprum, and conspecifics. Besides guarding, females roll, fan, and blow water on eggs to provide oxygen to the embryos. This behavior of female triggerfish is called "tending", and males rarely perform this behavior. A male triggerfish stays farther above the eggs and guards all the females and eggs in his territory. Males exhibit aggressive behaviors against conspecific males near the boundaries of their territories.

In crosshatch triggerfish (Xanthichthys mento) and yellow margin triggerfish (Pseudobalistes flavimarginatus), eggs are spawned in the morning and they hatch after the sunset on the same day. After hatching of embryos, the female crosshatch triggerfish leaves the male's territory. This mating system is an example of male-territory-visiting polygamy. Triggerfishes exhibit other types of mating systems, as well, such as a nonterritorial-female (NTF) polygyny and territorial-female (TF) polygyny. In NTF polygyny, nonterritorial females stay in the male's territory and reproduce. In TF polygyny, a female owns territory within a male's territory and will spawn in her territory.

Relation to humans

Some species of triggerfish, such as the titan triggerfish, may be ciguatoxic and should be avoided. Others, however, such as the grey triggerfish (Balistes capriscus), are edible.

Triggerfish species in focus

These species profiles show how members of the group differ. Their biology describes each named species, rather than every fish in the group.

Gray Triggerfish

The grey triggerfish (Balistes capriscus), or gray triggerfish, is a species of ray-finned fish in the triggerfish family Balistidae. The species is native to shallow parts of the western Atlantic from Nova Scotia to Argentina and also the eastern Atlantic, the Mediterranean Sea, and waters off Angola on the west coast of Africa.

In its appearance and habits, the grey triggerfish is a typical member of the genus Balistes except for its drab, uniformly grey coloration. It is a relatively small fish, usually less than 2.3 kg (5.1 lb) in weight. The Grey triggerfish is fished recreationally and, despite its tough skin, is an excellent food-fish. The species is classified as 'vulnerable' by the IUCN Red List.

Taxonomy

The Grey triggerfish was first formally described in 1789 by Johann Friedrich Gmelin with its type locality given as the Western North Atlantic, the Indian Ocean and the Mediterranean Sea. This species is classified in the genus Balistes which is the type genus of the family Balistidae, a family classified in the suborder Balistoidei in the order Tetraodontiformes.

Etymology

The grey triggerfish is classified in the genus Balistes, a name which refers to the first spine of the dorsal fin being locked in place by the erection of the shorter second trigger spine, and unlocked by depressing the second spine. Balistes is taken directly from the Italian pesca ballista, the "crossbow fish". Ballista originally being a machine for throwing arrows. The specific name capriscus is Latin for a "small goat", an allusion Gmelin did not explain, and it is likely to be a mistranslation of its Greek name dating to Aristotle, kápros, which means "boar"or kaprískos. its diminutive, an allusion to its sharp, powerful and perhaps also to a boar-like ferocity, as described by the Roman author and naturalist Claudius Aelianus in De Natura Animalium,"they fight even with fish of greater bulk and with the most skilled fishermen".

Distribution and habitat

The grey triggerfish is principally a fish of shallow waters in the western Atlantic Ocean. Its native range extends from Nova Scotia to the Caribbean Sea, the Gulf of Mexico and Bermuda, and southwards to Argentina. It is typically found over hard bottoms on reefs and rocky areas, in lagoons and in bays, at depths down to about 55 m (180 ft). It is also found on the other side of the Atlantic, around the British Isles, in the Mediterranean Sea and off the coast of Angola. It may have crossed the Atlantic as a result of the movement of water in the Gulf Stream and breeds in the Mediterranean.

Once considered to be an uncommon visitor to northern European seas, an increase in records around the Cornish coast, may indicate it is now breeding there; in addition, it has been found in other areas along the coast of Great Britain in recent years, suggesting that its range is continuing to expand northwards, with one caught as far north as the island of Tiree in the Inner Hebrides, Scotland.

Read the full species guide.

Queen Triggerfish

The queen triggerfish (Balistes vetula) is a large triggerfish species found in the tropical Atlantic Ocean. Its body coloration ranges from steel grey to olive green, but around the mouth are orange areas with striking electric blue rays. This species is commonly found in coral reefs or rocky bottoms of the sea. Its diet is mainly composed of shelled invertebrates like crabs and sea urchins. When breeding, the queen triggerfish dig a sandpit with its fin to lay eggs and fiercely defend eggs. This species is an important food fish among Caribbean communities, often harvested by hook-and-lines or fish traps.

Taxonomy

Balistes vetula was first formally described in the 10th edition of Systema Naturae published in 1758 with its type locality given as Ascension Island. In 1865 Pieter Bleeker designated this species as the type species of the genus Balistes. Balistes is the type genus of the family Balistidae, which is classified in the suborder Balistoidei in the order Tetraodontiformes.

Etymology

Balistes vetula is the type species of the genus Balistes, a name which refers to the first spine of the dorsal fin being locked in place by the erection of the shorter second trigger spine, and unlocked by depressing the second spine. Balistes is taken directly from the Italian pesca ballista, the "crossbow fish". Ballista originally being a machine for throwing arrows. The specific name vetula means "old woman"or"old wife", the Latin cognate of vieja, a Spanish name used in Cuba for this species which was recorded by the Cuban naturalist Antonio Parra in 1787. This name apparently follows a Portuguese tradition of some larger fishes common names which allude to women. George Shaw said "It is supposed to have obtained the popular title of Old Wife Fish from the appearance of the mouth when viewed in front, as well as from the slightly murmuring noise which it utters when first taken."

Distribution

The queen triggerfish could be found in the Atlantic waters, most commonly in warmer regions. In the Western Atlantic, its range spans from Massachusetts to Brazil, as well as the Caribbean Sea. It's most common in Florida, the Bahamas and the Caribbean. While on the Eastern Atlantic, its range stretches from the Azores to Southern Angola.

Read the full species guide.

Rough Triggerfish

Canthidermis maculata, also known as rough triggerfish or spotted oceanic triggerfish, is a species of triggerfish native to the tropical and subtropical oceans worldwide. Unlike most triggerfish, they are mostly pelagic.

In the Philippines, the species is locally called Tikos in the Cebuano language and is abundant in the Visayas and Mindanao island groups.

Distribution and habitat

In the western Pacific Ocean it ranges from the Gulf of Thailand north to the Yellow Sea and Japan, also extending eastward to the Philippines, Indonesia, and all the way to Polynesia and Hawaii. In the eastern Pacific Ocean, they are found from Mexico and around the Gulf of California down to Peru and the Galapagos Islands. Around the Indian Ocean, it ranges from the Red Sea and eastern Africa to the Seychelles, the Maldives, the Persian Gulf, India, Sri Lanka, the Andaman Sea, Australia, and Indonesia. Populations in the Atlantic Ocean range from New York down to the Gulf of Mexico, the Bahamas, the Caribbean Sea and down to Brazil on the western side. Around the eastern Atlantic Ocean, it ranges from the British Isles and the Bay of Biscay to the Azores, the Canary Islands and western Africa. Some populations are also found in South Africa. The spotted oceanic triggerfish inhabits warm waters high in biodiversity, characterized by strong surface currents and upwelling systems (Lezama-Ochoa et al., 2016). It can be found on deep slopes right offshore, in open water (Matsuura, 2001) and under fish aggregating devices (FADs), where they have been seen in groups of hundreds or thousands (Taquet et al., 2007).

Description

The maximum length for this species is 50 centimetres (20 in), but usually grows up to 35 centimetres (14 in). Adults and juveniles have different coloration. Adults are blue grayish, while juveniles are grayish black with white spots that fade over age. Adults may be seen with dark blotches appearing on the face and pectoral fins during mating. These markings are also present on females hovering above their nests, and may disappear within a few seconds once they ascend through in the water column, away from their nest (Clark et al., 2014). In this fish, the dorsal and anal fins are curved on the back. The dorsal fin of this species has from 23 to 27 rays; its first dorsal fin’s rays are spinous, with the first two rays more like sharp thorns. The smaller second thorn props up the longer first thorn, giving it the appearance of a trigger, after which the fish is named (Tupongov, 2015). Its anal fin has 20 to 27 rays. Adults and juveniles also have different caudal fin shapes: juveniles have rounded caudal fins and adults have concave ones.

Ecology

Canthidermis maculata are noted hosts of sea lice (Copepoda: Caligidae) in the Neotropical region (Morales-Serna et al., 2016). Additionally, they have been recorded as visitors of cleaning stations hosted by the black-nosed butterflyfish and the Mexican hogfish, at Malpelo Island in the tropical eastern pacific (Quimbayo et al., 2016).

Read the full species guide.

Range