{{Short description|Species of cartilaginous fish}} {{Distinguish|porcupine ray}} {{Speciesbox | image = Potamotrygon adventure aquarium2.jpg | status = NT | status_system = IUCN3.1 | status_ref = <ref name="iucn">{{cite iucn |author=Lucifora, L.O. |author2=Torres, Y.T.P. |author3=Charvet, P. |year=2025 |title=''Potamotrygon histrix'' |volume=2025 |article-number=e.T161657A893185 |doi=10.2305/IUCN.UK.2025-2.RLTS.T161657A893185.en |access-date=4 December 2025}}</ref> | genus = Potamotrygon | species = histrix | authority = (J. P. Müller & Henle, 1834) | synonyms = * ''Potamotrygon hystrix'' * ''Trygon hystrix'' }}
The '''porcupine river stingray''' ('''''Potamotrygon histrix''''', sometimes incorrectly modified to ''Potamotrygon hystrix''<ref>{{cite book |author1=Rosa, R.S. |author2=Charvet-Almeida, P. |author3=Quijada, C.C.D. | year=2010 | chapter=Biology of the South American Potamotrygonid Stingrays | pages=241–285 |editor1=Carrier, J.C. |editor2=Musick, J.A. |editor3=Heithaus, M.R. | title=Sharks and Their Relatives II: Biodiversity, Adaptive Physiology, and Conservation |series=Marine Biology |volume=20100521 | publisher=CRC Press | doi=10.1201/9781420080483-c5 |doi-broken-date=12 July 2025 |isbn=978-1-4200-8047-6 }}</ref>) is a species of river stingray in the family Potamotrygonidae, the type of the ''Potamotrygon'' genus. It is found in the basins of the Paraná and Paraguay River basins in South America.<ref name=fishbase>{{FishBase |Potamotrygon|hystrix |year=2017|month=October}}</ref> The population in the Rio Negro basin was described as a separated species, ''P. wallacei'', in 2016.<ref name=Carvalho2016>{{cite journal|author=Carvalho, M.R.d.|author2= Rosa, R.S. |author3= Araújo, M.L.G. |year=2016|title=A new species of Neotropical freshwater stingray (Chondrichthyes: Potamotrygonidae) from the Rio Negro, Amazonas, Brazil: the smallest species of ''Potamotrygon''|journal=Zootaxa|volume=4107|issue=4 |pages=566–586|doi= 10.11646/zootaxa.4107.4.5 |pmid= 27394840 }}</ref>
==Appearance== thumb|left|Dorsal and ventral view
Almost circular in shape, it grows up to {{convert|40|cm|in|abbr=on}} in disc width and {{convert|15|kg|lb|abbr=on}} in weight.<ref name=fishbase/> The upper surface is covered with denticles (sharp tooth-like scales). The coloration is light brownish with mottled patterns on the dorso, and pink on the ventral side. As with all stingrays, the mouth and gill openings are on the underside, and the eyes and gills exits are on the dorsal side.
===Sting=== Like other stingrays, the fish of this genus have venomous barbs at the base of their tails, and are dangerous to humans.<ref name=fishbase/><ref name="Dawes"/> The sting is replaced at roughly six-month intervals. It is an almost flat, barbed structure that can reach {{convert|6|cm|in|abbr=on}} in length, and is covered with a toxic mucus, making any attack a very painful one.<ref name=fishbase/>
The natives of South America are said to fear the stingray more than the piranha.<ref>{{cite book | title = Exotic Tropical Fishes | last = Axelrod | first = Herbert, R. | publisher = T.F.H. Publications. | year = 1996 | isbn = 0-87666-543-1}}</ref> However, they are not aggressive fish and not dangerous unless stepped on or otherwise threatened.
==Aquarium== [[File:Potamotrygon hystrix (bold).PNG|thumb|P. histrix, male (left) and female (right). Notice the two claspers on the male]]
Freshwater stingrays of the genus ''Potamotrygon'' are sometimes kept as exotic aquarium fish; though freshwater stingray of other genera do appear in the trade, most are from this genus. They are best kept with a deep, sandy substrate, in which they bury themselves, often with only their eyes visible. They are not territorial with other animals and can be kept in groups, provided a large enough aquarium is provided. They are carnivorous bottom-feeders and require strong filtration as they are rather sensitive to water conditions (any spike in NO<sub>2</sub> levels can kill them with no warning).<ref name="Dawes">{{cite book | title = Complete Encyclopedia of the Freshwater Aquarium | last = Dawes | first = John | publisher = Firefly Books Ltd. | location = New York | year = 2001 | isbn = 1-55297-544-4}}.</ref> Juvenile stingrays are unable to survive in waters that contain salinity over 20.6%.<ref>{{cite journal |author=Griffith, Robert W.|display-authors=et al|title=Serum Composition of Freshwater Stingrays (Potamotrygonidae) Adapted to Fresh and Dilute Sea Water|journal=Biological Bulletin|volume=144|issue=2 |year=1973|pages=304–320|doi=10.2307/1540010 |jstor=1540010 }}</ref> Like many species of stingrays, ''P. histrix'' has been bred in captivity, but they require a large tank. The male should be smaller than the female, as it is rather aggressive, biting the female during the mating process.<ref>{{cite web |title= Breeding of the raspy river stingray ''Potamotrygon scobina''|url= https://www.monsterfishkeepers.com/forums/showthread.php?203299-Breeding-of-the-Raspy-river-stingray-Potamotrygon-scobina|year= 2003|access-date=31 August 2012}}</ref> Males can be determined by the presence of claspers as in other chondrichthyans.<ref>{{cite web |title= Des reproductions régulières en aquarium|url= http://www.ivanov.ch/potamotrygon.htm|date= 2009-01-05|work=Véronique Ivanov |access-date=31 August 2012}}</ref>
==References== {{Reflist}}
{{Taxonbar|from=Q4548358}} {{Authority control}}
histrix Category:Freshwater fish of Argentina Category:Freshwater stingrays of Brazil Category:Fish of Paraguay Category:Fish of Uruguay Category:Fauna of the Pantanal Category:Fish described in 1834 Category:Taxa named by Johannes Peter Müller Category:Taxa named by Friedrich Gustav Jakob Henle