{{Short description|Species of fish}} {{Speciesbox | image = Assel-Kugelfisch 2.jpg | status = | status_system = | taxon = Colomesus asellus | authority = (J. P. Müller & Troschel, 1849) }}
'''''Colomesus asellus''''', the '''Amazon puffer''', '''asellus puffer''',<ref name="Ebert">{{cite book |author=Ebert, Klaus |year=2001 |title=The Puffers of Fresh and Brackish Water |publisher=Aqualog |isbn=3-931702-60-X}}</ref> '''South American freshwater puffer''',<ref name="Monks">{{cite book |editor=Monks, N. |title=Brackish Water Fishes |publisher=TFH |year=2006 |isbn=0-7938-0564-3}}</ref> '''Peruvian puffer''',<ref name="Ralph">{{cite book |author=Ralph, Chris |year=2003 |title=Pufferfish |publisher=Ringpress Books |isbn=1-86054-233-6}}</ref> or '''Brazilian puffer'''<ref name="Seriously Fish">{{cite web |title=Colomesus asellus – Amazon Puffer (Cheilichthys asellus, Chelichthys asellus) |website=Seriously Fish |url=https://www.seriouslyfish.com/species/colomesus-asellus/ |access-date=9 December 2023}}</ref> is a species of pufferfish confined to the Amazon, Essequibo and Orinoco basins in tropical South America.<ref name="FishBaseasellus"/> It is a popular aquarium species.<ref name=pufferforum>{{cite web|url=http://www.thepufferforum.com/forum/ug.php/v/PufferPedia/Freshwater/C_Asellus/|title=Colomesus asellus|accessdate=February 16, 2007|archive-url=https://web.archive.org/web/20070223231909/http://www.thepufferforum.com/forum/ug.php/v/PufferPedia/Freshwater/C_Asellus/|archive-date=February 23, 2007|url-status=dead}}</ref>
It has typically been recognized as the only true freshwater pufferfish of South America, but a study in 2013 recommended that the population in the Tocantins River basin (quite similar to ''C. asellus'' in appearance, but differs in genetics) should be considered as a separate species, ''C. tocantinensis''.<ref>Amaral, C.R.L.; P.M. Brito; D.A. Silva; and E.F. Carvalho (2013). A new cryptic species of South American freshwater pufferfish of the genus Colomesus (Tetraodontidae), based on both morphology and DNA data. PLoS ONE 8(9): e74397.</ref> This is followed by Catalog of Fishes,<ref>{{Cof genus |Colomesus|access-date=5 December 2018}}</ref> but not FishBase.<ref>{{FishBase genus | genus = Colomesus| month = December | year = 2018}}</ref>
==Description== The coloration of this fish is green above, white below, and patterned with black transverse bands across the dorsal surface. Compared with ''Colomesus psittacus'', the black bands on the back are much thicker, and it also has a distinctive black band that rings the base of the caudal fin.<ref name="Ebert"/> This species grows to a length of {{convert|12.8|cm|in}} SL.<ref name="FishBaseasellus">{{FishBase|genus= Colomesus|species= asellus |year=2012|month=October}}</ref> It is known to contain the toxin saxitoxin,<ref name="Freitas">{{cite journal |author=J. C. Freitas |year=2006 |title=Eating habits: are we safe to consume freshwater puffer fish from the Amazon region in Brazil? |journal=Journal of Venomous Animals and Toxins Including Tropical Diseases |volume=12 |issue=2 |pages=153–155 |url=http://www.scielo.br/pdf/jvatitd/v12n2/v12n2a01.pdf |doi=10.1590/s1678-91992006000200001|doi-access=free }}</ref> and gonyautoxin such as the GTX 2 and GTX 3.<ref>{{Cite journal|last1=Oliveira|first1=Joacir Stolarz|last2=Fernandes|first2=Solange Cristina Rego|last3=Schwartz|first3=Carlos Alberto|last4=Bloch|first4=Carlos|last5=Melo|first5=Jorge Alex Taquita|last6=Rodrigues Pires|first6=Osmindo|last7=de Freitas|first7=José Carlos|date=July 2006|title=Toxicity and toxin identification in Colomesus asellus, an Amazonian (Brazil) freshwater puffer fish|journal=Toxicon|volume=48|issue=1|pages=55–63|doi=10.1016/j.toxicon.2006.04.009|issn=0041-0101|pmid=16822534}}</ref>
==Ecology== ''Colomesus asellus'' is normally only found in freshwater environments although it will tolerate slightly brackish water.<ref name="Monks"/><ref name="FishBaseasellus"/>
Wild ''Colomesus asellus'' are reported to consume benthic crustaceans, fish, planktonic invertebrates, and plants.<ref name="FishBaseasellus"/> Aquarium specimens consume various invertebrates including midge larvae<ref name="Ebert"/> and Mysida.
Like other pufferfish, they have the ability to inflate themselves when threatened, making themselves much larger and therefore more difficult for predators to handle or swallow. ''Colomesus asellus'' is unusual among freshwater pufferfish for being migratory<ref name="Lima"/> and non-territorial.<ref name="Ebert"/>
''Colomesus asellus'' is known to breed during the wet season, spawning in rivers, with the numerous small eggs being scattered on the substrate and the larvae drifting downstream. ''Colomesus asellus'' is nearly impossible to breed in the aquarium because their eggs are very small and they go through a planktonic phase before growing into "real<nowiki>''</nowiki> fish.<ref name="Lima">{{cite journal |author1=Carlos Araujo-Lima |author2=Daniela Savastano |author3=Luciana Cardeliquio Jordao |year=1994 |title=Drift of ''Colomesus asellus'' (Teleostei: Tetraodontidae) larvae in the Amazon River |journal=Revue d'Hydrobiologie Tropicale |volume=27 |pages=33–38 |url=http://www.bondy.ird.fr/pleins_textes/cahiers/hydrob-trop/43866.pdf |access-date=2012-11-23 |archive-url=https://web.archive.org/web/20040504170645/http://www.bondy.ird.fr/pleins_textes/cahiers/hydrob-trop/43866.pdf |archive-date=2004-05-04 |url-status=dead }}</ref>
==In the aquarium== ''Colomesus asellus'' is fairly widely kept as an aquarium fish.<ref name="Ebert"/> An aquarium tank with volume of at least 109 liters is required ( approx. 29 US gallons). Compared to other freshwater pufferfish, ''Colomesus asellus'' is unusual in being tolerant of conspecifics and tends to be nervous when kept singly.<ref name=pufferforum/> It is known to be a fin-nipper and could attack slow moving species such as angelfish, guppies, and ''Corydoras''. ''Colomesus asellus'' has some of the fastest growing teeth of the freshwater puffers, so feeding crunchy foods and possibly having to do dentistry are two important factors.{{citation needed|date=February 2020}}
==References== {{Reflist}}
{{Taxonbar|from=Q13583745}}
Category:Tetraodontidae Category:Fish described in 1849