Arapaima gigasArapaima(Also: Giant arapaima)

Ge­o­graphic Range

Ara­paima gigas ex­clu­sively in­hab­its the Ama­zon River Basin of South Amer­ica.

(Gould­ing et al., 1993)

Habi­tat

Within the Ama­zon basin, A. gigas is found in sev­eral dif­fer­ent types of habi­tat, such as the flood­plain lakes of this re­gion, the large trib­u­taries of the Ama­zon river in­clud­ing the Rio Madera and the Rio Machado, and the varzea or for­est. The pi­rarucu in­hab­its both white water and clear water. Much of the water that com­prises the pi­rarucu's habi­tat is also oxy­gen de­fi­cient, as it is lo­cated in swampy areas of the rain­for­est.

(Lowe-Mc­Connell, 1987; Gould­ing, 1980)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Phys­i­cal De­scrip­tion

The pi­rarucu is one of the largest fresh­wa­ter fishes in the world. At one time, there were many in­di­vid­u­als over 3 me­ters in length that weighed more than 150 kilo­grams. The scales on a pi­rarucu this size can reach 6 cen­time­ters in length. How­ever, there are few pi­rarucu this size, if any, that are liv­ing cur­rently. The av­er­age size of this species has greatly re­duced due to over-fish­ing, though it is still com­mon to find pi­rarucu over 2 me­ters that weigh more than125 kilo­grams. The pi­rarucu is usu­ally grey in color with an or­ange speck­ling near its pos­te­rior end. There are also two sym­met­ri­cal fins on ei­ther side of the body at the pos­te­rior end. In­ter­est­ingly, A. gigas has a bony or toothed tongue, which is the source of the title os­teoglos­so­morph and a dis­tin­guish­ing char­ac­ter of those species in the order Os­teoglos­si­formes.

(Luna and Froese, 2002; Gould­ing, 1993; Gould­ing, 1980; Smith, 1981).

  • Range mass
    200 (high) kg
    440.53 (high) lb
  • Range length
    450 (high) cm
    177.17 (high) in

De­vel­op­ment

The fe­male pi­rarucu is sex­u­ally ma­ture at the age of five years old and are typ­i­cally 160 cen­time­ters in length at this point in their life.

(Queiroz, 1998)

Re­pro­duc­tion

Due to the ge­o­graphic range that A. gigas in­hab­its, the an­i­mal's life cycle is greatly af­fected by the sea­sonal flood­ing that oc­curs. Half of the year the pi­rarucu ex­pe­ri­ences an abun­dance of water, which is a ben­e­fit to these aquatic or­gan­isms; how­ever, the other half of the year the pi­rarucu ex­pe­ri­ences drought con­di­tions. The pi­rarucu has adapted to this great fluc­tu­a­tion in many as­pects of it's life, in­clud­ing re­pro­duc­tion. A. gigas lays it's eggs dur­ing the months of Feb­ru­ary, March, and April when the water lev­els are low. They build a nest ap­prox­i­mately 50 cm wide and 15 cm deep, usu­ally in sandy bot­tomed areas. As the water rises the eggs hatch and the off­spring have the flood sea­son to pros­per, dur­ing the months of May to Au­gust. There­fore, the yearly spawn­ing is reg­u­lated sea­son­ally. A. gigas is a mouth-brooder.

(Lowe-Mc­Connell 1987; Smith 1981, Luna and Froese, 2002)

  • Breeding season
    In drought season, usually during the months of February-April

A. gigas has been known to guard both the eggs and the off­spring them­selves. The parental care in­cludes help­ing to aer­ate the water for it's off­spring, which is a ne­ces­sity for sur­vival of the off­spring in the oxy­gen-de­fi­cient wa­ters of some habi­tats. Adults have the abil­ity to exude a pheromone from their head to at­tract off­spring and keep them in close prox­im­ity.

(Lowe-Mc­Connell, 1987; Luna and Froese, 2000)

Be­hav­ior

Com­mu­ni­ca­tion and Per­cep­tion

A. gigas com­mu­ni­cates with it's off­spring by means of at­trac­tive pheromones, which keep the off­spring near the par­ents.

(Lowe-Mc­Connell, 1987)

Food Habits

A. gigas is a preda­tor that mainly eats other fish. If a bird or some other an­i­mal hap­pens to be pre­sent, this large preda­tor will also eat that an­i­mal. The pi­rarucu usu­ally finds food near the top of the water be­cause it is an ob­lig­ate air breather that needs to sur­face every 10-20 min. How­ever, the pi­rarucu is also ca­pa­ble of div­ing.

(Lowe-Mc­Connell, 1987; Gould­ing, 1980)

Pre­da­tion

The pi­rarucu's sheer size and bony armor pro­vide de­fenses against preda­tors.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

A. gigas is hunted and uti­lized in many ways by local human pop­u­la­tions. Pi­rarucu are har­pooned or caught in large nets and the meat is said to be de­li­cious. One in­di­vid­ual can yield sev­enty kilo­grams of meat. In ad­di­tion, the pi­rarucu's bony tongue is often used to scrape cylin­ders of dried guarana, an in­gre­di­ent in a bev­er­age, and the bony scales are used as nail files. This an­i­mal also ap­pears in the pet trade, al­though to keep a pi­rarucu cor­rectly re­quires a large tank and can prove quite dif­fi­cult.

(Smith, 1981)

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse ef­fects to­wards Homo sapi­ens.

Con­ser­va­tion Sta­tus

In 1976, the SUDEPE (Su­per­tenden­cia do De­sen­volvi­mento da Pesca) out­lawed the killing of a pi­rarucu from Oc­to­ber to March, dur­ing the low water sea­son when this an­i­mal be­comes so vis­i­ble due to it's sheer size. Also the SUDEPE de­clared that the pi­rarucu has to be at least one and a half me­ters in length be­fore it can be killed.

(Smith, 1981; Gould­ing, 1980)

Other Com­ments

A. gigas was first named by Georges Cu­vier in 1817. This an­i­mal is often called a liv­ing fos­sil due to it's ar­chaic mor­phol­ogy. This fish has also been ex­tremely suc­cess­ful in the Ama­zon. How­ever, due to over­fish­ing this an­i­mal is in dan­ger of be­com­ing ex­tinct.

Con­trib­u­tors

William Fink (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Lewis Melfi (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

external fertilization

fertilization takes place outside the female's body

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

piscivore

an animal that mainly eats fish

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

Ref­er­ences

Gould­ing, M. 1980. Fishes and the For­est, Ex­plo­rations in Ama­zon­ian Nat­ural His­tory. Berke­ley: Uni­ver­sity of Cal­i­for­nia Press.

Gould­ing, M., N. Smith, D. Mahar. 1993. Floods of For­tune. New York: Co­lum­bia Uni­ver­sity Press.

Lowe-Mc­Connell, R. 1987. Eco­log­i­cal Stud­ies in Trop­i­cal Fish Com­mu­ni­ties. Lon­don: Cam­bridge Uni­ver­sity Press.

Luna, S., R. Froese. 13/05/03. "Fishbase.​org" (On-line). Ac­cessed 11-2-02 at http://​www.​fishbase.​org/​Summary/​SpeciesSummary.​cfm?​ID=2076&​genusname=Arapaima&​speciesname=gigas.

Queiroz, H. De­cem­ber 1998. Growth and sex­ual mat­u­ra­tion of fe­male pi­rarucu, *Ara­paima gigas*: tools for con­ser­va­tion and man­age­ment of an Ama­zon­ian fish. Jour­nal of Fish Bi­ol­ogy, Vol­ume 53, Sup­ple­ment A: 441-442.

Smith, N. 1981. Man, Fishes, and the Ama­zon. New York: Co­lum­bia Uni­ver­sity Press.