Canthidermis maculata

In the western Pacific Ocean it ranges from the Gulf of Thailand north to the Yellow Sea and Japan,^[1] also extending eastward to the Philippines, Indonesia, and all the way to Polynesia and Hawaii.^[1] In the eastern Pacific Ocean, they are found from Mexico and around the Gulf of California down to Peru and the Galapagos Islands.^[1] 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.^[1] 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.^[1] 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.^[1] Some populations are also found in South Africa.^[1] 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).

The maximum length for this species is 50 centimetres (20 in), but usually grows up to 35 centimetres (14 in).^[1] Adults and juveniles have different coloration.^[1][2] Adults are blue grayish, while juveniles are grayish black with white spots that fade over age.^[2] 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;^[2] 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.^[2] Adults and juveniles also have different caudal fin shapes: juveniles have rounded caudal fins and adults have concave ones.^[2]

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).

Spotted oceanic triggerfish display plasticity in their eating habits, being considered either a carnivorous or a planktivorous fish. Upon examination, they have been shown to consume smaller fish, Halobates (sea skaters), Siphonophores, and smaller cartilaginous fish (Senta et al., 1993).

The oceanic triggerfish falls prey to large pelagic fish such as the Indo-Pacific Sailfish (Varghese et al., 2013), the dolphinfish (Mahi-mahi) (Oxenford et al., 1999), and sea birds such as Streaked Shearwaters which are found in Japan (Matsumoto et al., 2012). Additionally, eggs in nests that are not defended by a mother oceanic triggerfish are known to be preyed upon by smaller opportunistic fish such as the goatfish, Parupeneus multifasciatus, the checkerboard wrasse, Halichoeres hortulanus, as well as other triggerfish such as the orange-lined triggerfish, Balistapus undulates, and the titan triggerfish, Balistapus viridescens (Clark et al., 2014).

Canthidermis maculata are known to gather in large groups, hundreds and sometimes thousands (Taquet et al., 2007) and are frequently associated with FADs.^[2] These aggregations may also include other species such as the sleek unicorn surgeonfish, Naso hexacanthus. Oceanic triggerfish are currently thought to move as a group, migrating together from the open ocean to shallower waters for nesting purposes, and returning together to the open ocean once nesting is complete. They are typically nonaggressive, shy, and easily scared away from their nests when confronted by bigger fish such as the titan triggerfish, and divers. It is likely, due to diver observations of courtship patterns, that only female oceanic triggerfish exhibit nest guarding behaviors and though easily scared away by larger fish, will defend their nest from smaller carnivorous fish such as goatfish and wrasse (Clark et al., 2014).

This fish species shows some importance to commercial fishing.^[1] The spotted oceanic triggerfish, like other triggerfish, is sold at local markets in coastal Asian countries as a fish to be eaten. These triggerfish are not typically fished for specifically but rather are caught as by-catch in tuna purse seine fishing and on longlines (Sethi et al., 2011; Lezama-Ochoa et al., 2016, Matsuura, 2001). Additionally, the spotted oceanic triggerfish is sold in the aquarium trade.^[1]

There have been reports of ciguatera poisoning in some humans that consumed the fish.^[1]

Fishermen living in the town of Kinniya,^[3] Sri Lanka, use this species in marine fish production.^[4]