Triggerfish

The largest member of the family, the stone triggerfish (Pseudobalistes naufragium) reaches 1 m (3.3 ft),[4] but most species have a maximum length between 20 and 50 cm (8–20 in).[2]

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. The eyes are small, set far back from the mouth, at the top of the head. The anterior dorsal fin is reduced to a set of three spines. The first spine is stout and by far the longest. All three are normally retracted into a groove. 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. The sickle-shaped caudal fin is used only to escape 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. Gill plates (opercula), although present, are also not visible, overlaid by the 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. This peculiar covering of the gill plates is shared with other members of the Tetradontae. 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.

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".

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

Image	Genus	Living species
	Abalistes D. S. Jordan & Seale, 1906	Abalistes filamentosus Matsuura & Yoshino, 2004 Abalistes stellaris (Bloch & J. G. Schneider, 1801) Abalistes stellatus Anonymous, referred to Lacépède, 1798
	Balistapus Tilesius, 1820	Balistapus undulatus M. Park, 1797
	Balistes Linnaeus, 1758	Balistes capriscus J. F. Gmelin, 1789 Balistes polylepis Steindachner, 1876 Balistes punctatus J. F. Gmelin, 1789 Balistes vetula Linnaeus, 1758
	Balistoides Fraser-Brunner, 1935	Balistoides conspicillum (Bloch & J. G. Schneider, 1801) Balistoides viridescens (Bloch & J. G. Schneider, 1801)
	Canthidermis Swainson, 1839	Canthidermis macrolepis Boulenger, 1888 Canthidermis maculata Bloch, 1786 Canthidermis sufflamen Mitchill, 1815
	Melichthys Swainson, 1839	Melichthys indicus J. E. Randall & Klausewitz, 1973 Melichthys niger Bloch, 1786 Melichthys vidua J. Richardson, 1845
	Odonus Gistel, 1848	Odonus niger Rüppell, 1836
	Pseudobalistes Bleeker, 1865	Pseudobalistes flavomarginatus Rüppell, 1829 Pseudobalistes fuscus (Bloch & J. G. Schneider, 1801) Pseudobalistes naufragium D. S. Jordan & Starks, 1895
	Rhinecanthus Swainson, 1839	Rhinecanthus abyssus Matsuura & Shiobara, 1989 Rhinecanthus aculeatus Linnaeus, 1758 Rhinecanthus assasi Forsskål, 1775 Rhinecanthus cinereus Bonnaterre, 1788 Rhinecanthus lunula J. E. Randall & Steene, 1983 Rhinecanthus rectangulus Bloch & J. G. Schneider, 1801 Rhinecanthus verrucosus Linnaeus, 1758
	Sufflamen D. S. Jordan, 1916	Sufflamen albicaudatum Rüppell, 1829 Sufflamen bursa Bloch & J. G. Schneider, 1801 Sufflamen chrysopterum Bloch & J. G. Schneider, 1801 Sufflamen fraenatum Latreille, 1804 Sufflamen verres C. H. Gilbert & Starks, 1904
	Xanthichthys Kaup, 1856	Xanthichthys auromarginatus E. T. Bennett, 1832 Xanthichthys caeruleolineatus J. E. Randall, Matsuura & Zama, 1978 Xanthichthys greenei Pyle & Earle, 2013 Xanthichthys lineopunctatus Hollard, 1854 Xanthichthys mento D. S. Jordan & C. H. Gilbert, 1882 Xanthichthys ringens Linnaeus, 1758
	Xenobalistes Matsuura, 1981	Xenobalistes punctatus Heemstra & M. P. Smith, 1983 Xenobalistes tumidipectoris Matsuura, 1981

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 will also take small fishes and some, notably the members of the genus Melichthys, feed on algae.[2] A few, for example the redtoothed triggerfish (Odonus niger), mainly feed on plankton.[2] They are known to exhibit a high level of intelligence for a fish, and have the ability to learn from previous experiences.[3][5]

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.[6]

Spawning and biparental care

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.[9]

The titan triggerfish can move relatively large rocks when feeding and is often followed by smaller fish, in this case orange-lined triggerfish and moorish idol, that feed on leftovers.

Male and female triggerfish perform certain prespawning behaviors: blowing and touching.[8] A male and female 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)[9][10] and are easily spread by waves. 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, thereby inducing hatching.[11] 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.

Triggerfish lay their demersal eggs in a small hole dug in the sea bottom. 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.[12]

Grey triggerfish caught off the coast of Madeira

Some species of triggerfish, such as the titan triggerfish, may be ciguatoxic and should be avoided.[2] Others, however, such as the grey triggerfish (Balistes capriscus), are edible.[13]

• 
  The reef triggerfish is the state fish of Hawaii.
• 
  Most triggerfish are aggressive, but few match the orange-lined triggerfish.[3]
• 
  The gilded triggerfish is among the few sexually dimorphic triggerfish. The female lacks the blue throat and yellow fin-edging.
• 
  The redtoothed triggerfish is one of the relatively few planktivores of the family.
• 
  The queen triggerfish has elegant extensions to its fins.
• 
  Adult sargassum triggerfish live around reefs and banks, but juveniles live around sargassum.

• Media related to Balistidae at Wikimedia Commons
• Data related to Balistidae at Wikispecies
• The dictionary definition of Balistidae at Wiktionary