Piaractus brachypomus

Piaractus brachypomus
	Adult Piaractus brachypomus
Conservation status
	; Least Concern (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Characiformes
Family:	Serrasalmidae
Genus:	Piaractus
Species:	P. brachypomus
Binomial name
	Piaractus brachypomus; (G. Cuvier, 1818)
Synonyms
	Colossoma bidens; Colossoma brachypomum

Piaractus brachypomus, the Red-Bellied Pacu, is a large species of pacu, a close relative of piranhas and silver dollars, in the serrasalmid family.^[1]^[2] It is native to the Amazon basin in tropical South America, but it formerly included populations in the Orinoco, which was described in 2019 as a separate species, P. orinoquensis.^[3] Additionally, P. brachypomus is widely farmed and has been introduced to other regions.^[4] In South Florida they are invasive in rivers, canals or lakes.^[5]

As with a number of other closely related species, P. brachypomus is often referred to as the red-bellied pacu in reference to the appearance of the juveniles. This has resulted in a great deal of confusion about the nature and needs of all the species involved, with the reputation and requirements of one frequently being wrongly attributed to the others.^[6]

Ecology

In general, its behavior resembles that of the closely related tambaqui (Colossoma macropomum). It is migratory, but the pattern is poorly understood.^[7] Spawning occurs at the beginning of the flood season between November and February.^[8] Larvae of the pirapitinga are found in whitewater rivers, but adults mainly live in flooded forests and floodplains of various river types, including those of both nutrient-rich and nutrient-poor.^[7] Unlike the tambaqui, the Red bellied pacu also occurs in the headwaters of nutrient-poor rivers (not just in the lower sections).^[7]

It mainly feeds on fruits, seeds, and nuts, but it is opportunistic and will also take zooplankton, insects, crustaceans and small fish, especially in the dry season.^[4]^[9] In general, more seeds are able to pass undamaged through the red bellied pacu than the tambaqui, meaning that the former is overall a more efficient seed disperser.^[10]

Appearance

Piaractus brachypomus can reach up to 88 cm (2.9 ft) in length and 25 kg (55 lb) in weight.^[2]

Juveniles have a distinct red chest and stomach, and are easily confused with the carnivorous red-bellied piranha (Pygocentrus nattereri), but the two can be separated by their teeth, which are molar-like in Piaractus brachypomus.^[1] This similarity is believed to be Batesian mimicry by P. brachypomus in an attempt of avoiding predation by other species.^[4] Adults lack the bright red chest and belly, and resemble the tambaqui (Colossoma macropomum), but can be separated by several meristic and morphological features: The Red Bellied Pacu has a smaller adipose fin that lacks rays, as well as differences in teeth and operculum.^[1]^[11] The pirapitinga also has a more rounded head profile (less elongated and pointed).^[11]^[12] The other member of its genus, P. mesopotamicus, can be distinguished by its smaller scale-size^[13] and the higher number of lateral scales (more than 110).^[1]

Connection to humans

The Red Bellied Pacu supports major fisheries and based on a review by IBAMA, it was the 12th most caught fish by weight in the Brazilian Amazon in 1998 (just after the tambaqui).^[7]

The Red Bellied Pacu is often kept in aquaculture. Hybrids between this species and the tambaqui have been produced in aquaculture.^[14] It can also hybridize with P. orinoquensis, but the offspring appears to be sterile.^[3]

References

^ ^a ^b ^c ^d ^e ^f Nico, L.; P. Fuller; and M. Neilson (22 October 2013). Piaractus brachypomus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. Retrieved 2 March 2017.
^ ^a ^b Froese, Rainer; Pauly, Daniel (eds.) (2017). "Piaractus brachypomus" in FishBase. March 2017 version.
^ ^a ^b Escobar, M.D., R.P. Ota, A. Machado-Allison, I.P. Farias and T. Hrbek (2019). A new species of Piaractus (Characiformes: Serrasalmidae) from the Orinoco Basin with a redescription of Piaractus brachypomus. Journal of Fish Biology: [1-x]. doi:10.1111/jfb.13990
^ ^a ^b ^c SeriouslyFish: Piaractus brachypomus. Retrieved 2 March 2017.
^ Everglades Cooperative Invasive Species Management Area
^ Gamefish of the Amazon Basin, Tambaqui and Pirapitinga
^ ^a ^b ^c ^d Araujo-Lima, C.A.R.M.; and M.L. Ruffino (2003). Migratory Fishes of the Brazilian Amazon. Pp. 233—302 in: Carolsfeld, J.; B. Harvey; C. Ross; and A. Baer (editors). Migratory Fishes of South America. ISBN 9781552501146
^ Nascimentoa, A.F.; A.N. Maria; N.O. Pessoa; M.A.M. Carvalho; A.T.M. Viveiros (2010). "Out-of-season sperm cryopreserved in different media of the Amazonian freshwater fish Red bellied Pacu (Piaractus brachypomus)". Animal Reproduction Science. 118 (2–4): 324–329. doi:10.1016/j.anireprosci.2009.07.002. PMID 19679412.
^ Hintz, B. (2012). "Piaractus brachypomus". Animal Diversity Web. Retrieved 13 March 2017.
^ Lucas, Christine M. (September 2008). "Within Flood Season Variation in Fruit Consumption and Seed Dispersal by Two Characin Fishes of the Amazon". Biotropica. 40 (5): 581–589. Bibcode:2008Biotr..40..581L. doi:10.1111/j.1744-7429.2008.00415.x. JSTOR 20492487. S2CID 85788776.
^ ^a ^b Lauzanna, L.; and G. Loubens (1985). Peces del Rio Marmoré. ISBN 2-7099-0779-8.
^ Cagauan, A.G (2007). Red-bellied Pacu in the Philippines. Journal of Environmental Science and Management 10(1): 42—47.
^ OPEFE (27 December 2011). genus Piaractus. Retrieved 2 March 2017.
^ Gomes, Schneider, Barros, Sampaio, Hashimoto, Porto-Foresti, and Sampaio (2012). Innovative molecular approach to the identification of Colossoma macropomum and its hybrids. An. Acad. Bras. Ciênc. 84(2).