Lagoon Triggerfish

A reef triggerfish is easily distinguished by its angular body, distinctive color pattern (resembling blocks of colors), fin arrangement, and characteristic dorsal spine. This forward spine on the dorsal fin lies slightly above and behind the eye. It is very strong and rigid, serving as defense adaptation. When this spine is raised, it often locks in this protective position, giving the triggerfish its name. Altogether, there are three dorsal spines, twenty-three to twenty-six dorsal softrays, twenty-one to twenty-three anal softrays, and no anal spines (Michael 1998). Considered to be sturdy and well-built, the reef triggerfish reaches a maximum length of thirty centimeters (Tinker 1982). It has a small but powerful jaw, equipped with sharp, cutting teeth. The eyes of a reef triggerfish are set atop the head, moving independently, so as to scan the reef for possible predators and prey (Hoover 1993).

Other Physical Features: bilateral symmetry

In 1984-85, the reef triggerfish was voted the official State Fish of Hawaii, as it is historical for the state, and is one of the most abundant and widely recognized Hawaiian fishes. The official term of office lasted for five years, and upon its culmination there was no re-election campaign. Though the reef triggerfish was not re-elected into office, it remains the unofficial State Fish of Hawaii. Hawaiians have given the reef triggerfish the common name of Humu-humu-nuku-nuku-apu'a (Waikiki Aquarium Education Department 1999). Also widely known as the Picasso triggerfish, the reef triggerfish shares its scientific name with its less common relative, the lagoon triggerfish (Michael 1998).

Perception Channels: tactile ; chemical

Currently abundant in many marine environments, the reef triggerfish is not presently at risk. However, major alterations are occurring in many of these habitats, carrying the potential to greatly reduce their numbers. In additon to tropical fish collectors, human population growth and the factors that accompany it pose threats to reef triggerfish, as well as other marine fishes and organisms. Though currently not at risk, other organisms in many of the reef triggerfish's habitats are being greatly reduced by abiotic factors (Dresie 1999).

US Federal List: no special status

CITES: no special status

Caught with drive-in nets, reef triggerfish satisfy minor commercial fisheries purposes, but have a high commercial value for aqauriums. Reef triggerfish are considered good aquarium fish, as they are hardy and easy to keep and maintain. The ability of the fish to feed upon a wide variety of items, from live to frozen and flake foods, makes it very marketable among aquariums. With no special requirements for temperature or light conditions, the reef triggerfish is relatively versatile in its ability to adapt to environmental conditions. As it is easily caught and therefore readily available for purchase, the reef triggerfish is popular, also due to its unusual markings and vibrant color (Waikiki Aquarium Education Department 1999). The reef triggerfish also has a good disposition relative to other kinds of triggerfish. The reef triggerfish is not currently highly valued as a commercial food item for the majority of the human population. However, early Hawaiians ate it infrequently. The fish was also dried and utilized as a cooking fuel by early Hawaiians when other sources of fuel were in short supply. More importantly, the reef triggerfish was used further as a substitute for pigs for some religious ceremonies (Hoover 1993).

The reef triggerfish diet consists mainly of reef invertebrates and algae. Common food items are small crustaceans, worms, brittlestars, sea urchins, and snails. Less common dietary supplements are other fishes, corals, tunicates, forams, and eggs. Highly versatile in its feeding possibilities, the reef triggerfish will feed on a wide variety of crustaceans, molluscs, and fish. Reef triggerfish obtain their food primarily by rooting through sand or rocks (Animal World 2000; Tinker 1982).

Considered to live in the Indo-Pacific region, reef triggerfish transverse a wide variety of marine areas from thirty degrees north to south in latitude (Michael 1998). Reef triggerfish extend from the Hawaiian islands southward to Polynesia and Australia, westward through Micronesia and Melanesia, through the East Indies including the Philippines, across the Indian Ocean, to the coast of Africa and the Red Sea. More specifically, reef triggerfish occupy the Red Sea south to South Africa, east to the Hawaiian, Marquesas, and Tuamotu Islands, north to southern Japan, south to Lord Howe Island, Micronesia, and the Eastern Atlantic from Senegal to South Africa (Allen and Steen 1994).

Biogeographic Regions: australian (Native ); oceanic islands (Native ); indian ocean (Native ); pacific ocean (Native )

The reef triggerfish is generally found in shallow outer reef habitats. Swimming along the bottom in search of food items, it is found on surge-swept basalt reefs. The reef triggerfish is commonly found in subtidal reef flats and protected lagoons (Hoover 1993). This marine fish usually occupies water with salinity levels ranging from 1.020 to 1.023, and water temperatures from seventy-seven to eighty degrees Fahrenheit (Tinker 1982).

Aquatic Biomes: reef ; coastal

Like most fishes, the reef triggerfish undergoes heterosexual reproduction, in which there are separate male and female parents. Reef fishes are egg-layers, and the eggs are externally fertilized by the male parent. Nests are built by the female parent, in which the eggs are fertilized and cared for until they hatch. The newly-hatched young are also looked after by the female parent (Hoover 1993).

Distinct pairing (Ref. 205). Mating system may be a mixture of polygyny, monogamy, and potential promiscuity in solitary females but the primary mating system considered for this species is polygyny (Ref. 116439). Females are territorial, solely tending and guarding the eggs (Ref. 116451). Males exhibit polygyny (Ref. 116451).

Description: Characterized by generally whitish body color with yellow band from snout intersecting with dark bar through eye; dark brown area on middle of body connected to diagonal dark bands above anal fin; caudal fin base with rows of black dots; front of eye with deep groove; nearly straight dorsal and ventral head profiles; small, anterior projecting spines on caudal peduncle and adjacent posterior body in three horizontal rows; rounded caudal fin (Ref. 90102).

Dorsal spines (total): 3; Dorsal soft rays (total): 23 - 26; Analspines: 0; Analsoft rays: 21 - 23

Commonly found in subtidal reef flats and shallow protected lagoons. Territorial. Feed on algae, detritus, mollusks, crustaceans, worms, sea urchins, fishes, corals, tunicates, forams, and eggs (Ref. 3921). Also caught with drive-in nets and is considered a popular aquarium fish (Ref. 9770).

Commonly found in subtidal reef flats and shallow protected lagoons, Ref. 48637. Benthopelagic (Ref. 58302). Juveniles secretive with rubble patches, adults swim about openly but are usually shy (Ref. 48637). Territorial. Feed on algae, detritus, mollusks, crustaceans, worms, sea urchins, fishes, corals, tunicates, forams, and eggs (Ref. 3921). Oviparous (Ref. 205). Sleep on its side; makes a whirring noise when alarmed (Ref. 4420). Also caught with drive-in nets and is considered a popular aquarium fish (Ref. 9770).

fisheries: minor commercial; aquarium: commercial; price category: medium; price reliability: very questionable: based on ex-vessel price for species in this family

Rhinecanthus aculeatus (Linnaeus)

The levator arcus palatini is poorly developed, with only a few fibers to the anterodorsal face of the hyomandibular, while the levator operculi is well developed, extending inward beneath the dilatator operculi to the ventral process of the pterotic.

The cutaneous portion of the protractor hyoidei is well developed, and there is a fifth section of the hyohyoidei abductors. The sternohyoideus is as was described for B. undulatus.

The fifth levator externus is well developed, and partially fused to the fourth levator anterodorsally. Transversus dorsalis II arises only from the parasphenoid.

The posterior region of the groove in the pelvis which contains the arrector ventralis pelvicus has closed over ventrally to form a tube. The tendon remains single throughout its length, but divides immediately before its insertion.

分布於印度-太平洋區，西起紅海、非洲東岸，東至土木土及馬貴斯群島，北至日本南部，南至羅得豪島。台灣除西部及澎湖外，皆有分布。

通常以陷阱法、潛水或流刺網捕獲，以生鮮或醃製於市場出售，或以其可愛的模樣而常被飼養於水族館中，供人欣賞。

體稍延長，呈長橢圓形， 尾柄短。口端位，齒白具缺刻。眼前無深溝。頰部被鱗；鰓裂後有大型骨質鱗片。背鰭兩個，基底相接近，第一背鰭位於鰓孔上方，第I棘粗大，第II棘則細長，第III背鰭棘極短，不明顯，不露出棘基深溝。尾柄具三列小棘，上兩列向前延伸至第二背鰭後半部下方，最後一列很短，只侷限在尾柄部份。體背部褐色，腹部白色；從眼到胸鰭基部有一鑲細藍線之褐色帶，此帶中央亦具一條細藍線；眼眶隔藍色，上有三條黑線；有一藍帶圍著上唇；從口部有一橘帶延伸至胸鰭基下方；體中央偏上有一大黑斑，自此黑斑延伸至臀鰭基具數條窄黑帶，彼此以白色帶相隔；另有兩條寬黑帶延伸至第二背鰭基部；尾柄小棘黑色。除第一背鰭黑色外，其餘鰭均為白色，但尾鰭稍具深黃色。

主要棲息於淺的潟湖區及亞潮帶礁區，一般被發現於水深50公尺內的水域，領域性強。主要以藻類、碎屑、海膽、甲殼類等小型甲殼類、水螅體、被囊動物、軟體動物及小魚等為食。

The lagoon triggerfish (Rhinecanthus aculeatus), also known as the blackbar triggerfish, the Picasso triggerfish, or the Picassofish, is a triggerfish, up to 30 cm in length, found on reefs in the Indo-Pacific region.

This species has been studied in a range of research contexts, from locomotion to color vision research.

Commonly found in subtidal reef flats and shallow protected lagoons. Territorial. Feeds on algae, detritus, molluscs, crustaceans, worms, sea urchins, fishes, corals, tunicates, forams, and eggs. Also caught with drive-in nets and is considered a popular aquarium fish (Ref. 9770).