Iridescent shark

The fish is named for the glow or iridescence exhibited in juveniles, as well as the shark-like appearance of this and other shark catfish.

Adults reach up to {{convert|130|cm|ft|abbr=on}} in length and can weigh up to a maximum of {{convert|44|kg|lb|abbr=on}}. They have a shiny, iridescent color that gives these fish their name. However, large adults are uniformly grey. The fins are dark grey or black. Juveniles have a black stripe along the lateral line and a second black stripe below the lateral line.

File:P hypophthalmus migrations.gif

Orange: March to May

Dark green: May to September

Red: October to February

Shaded region: spawning region of the southern Mekong population between Khone Falls and Kratie]]

Iridescent sharks originate in the large rivers Chao Phraya and Mekong in Asia, though they have been introduced into other rivers for aquaculture. They are a freshwater fish that natively live in a tropical climate and prefer water with a 6.5–7.5 pH, a water hardness of 2.0–29 dGH, and a temperature range of {{convert|22|-|26|°C|°F|abbr=on}}.{{FishBase|genus= Pangasianodon |species= hypophthalmus| month = February | year = 2012}} They can tolerate hypoxic conditions thanks to their swim bladder which can be used as an air-breathing organ.{{cite journal |last1=Ma |first1=Xiaoli |last2=Shang |first2=Mei |last3=Su |first3=Baofeng |last4=Wiley |first4=Anne |last5=Bangs |first5=Max |last6=Alston |first6=Veronica |last7=Simora |first7=Rhoda Mae |last8=Nguyen |first8=Mai Thi |last9=Backenstose |first9=Nathan J. C. |last10=Moss |first10=Anthony G. |last11=Duong |first11=Thuy-Yen |last12=Wang |first12=Xu |last13=Dunham |first13=Rex A. |title=Comparative Transcriptome Analysis During the Seven Developmental Stages of Channel Catfish (Ictalurus punctatus) and Tra Catfish (Pangasianodon hypophthalmus) Provides Novel Insights for Terrestrial Adaptation |journal=Frontiers in Genetics |date=2021 |volume=11 |doi=10.3389/fgene.2020.608325 |doi-access=free |pmid=33552125 |pmc=7859520 |issn=1664-8021}} They prefer large bodies of water similar to the deep waters of their native Mekong river basin.

The iridescent shark is a migratory fish that in most regions moves upstream to spawn during the flood season while the waters are high and returns downstream to seek rearing habitats when the river water levels recede. The dates of the migrations vary depending on the river system. In the Mekong river basin, they migrate upstream in May to July and return downstream during September through December. South of the Khone Falls, upstream migration occurs in October to February, with its peak in November to December; here, it appears to be triggered by receding waters at the end of the flood season.

In August 2015, an environmental group in Santander, Colombia, confirmed that iridescent sharks had been found in one of the tributaries that feed into the Magdalena River, having been accidentally introduced from illegal farm fisheries in the area. The find has caused alarm amongst the scientific community and government officials, as the Magdalena river is home to over 200 native fish species, 35 of which are endangered.{{cite news |last1=Alarcón |first1=Laura Betancur |url= http://www.eltiempo.com/estilo-de-vida/ciencia/pez-basa-esta-en-el-magdalena/16391799|title=Alerta por amenaza del pez basa en el río Magdalena| newspaper=El Tiempo |language = es| date=1 October 2015}}

Disruption to these sharks can come from many physical stressors, including but not limited to shear forces, rapid decompression, blade strike and turbulence. These can lead to and have led to an increase in the Injury and mortality rate of these sharks. This is a sad reality{{citation needed|date=March 2023}} since these injured can be caused by hydropower developments which are being put into place to combat the global climate crisis that is being faced.{{Cite journal |last1=Colotelo |first1=A. H. |last2=Mueller |first2=R. P. |last3=Harnish |first3=R. A. |last4=Martinez |first4=J. J. |last5=Phommavong |first5=T. |last6=Phommachanh |first6=K. |last7=Thorncraft |first7=G. |last8=Baumgartner |first8=L. J. |last9=Hubbard |first9=J. M. |last10=Rhode |first10=B. M. |last11=Deng |first11=Z. D. |date=2018 |title=Injury and mortality of two Mekong River species exposed to turbulent shear forces |journal=Marine and Freshwater Research |volume=69 |issue=12 |pages=1945 |doi=10.1071/mf18126 |issn=1323-1650|doi-access=free |bibcode=2018MFRes..69.1945C }}

Iridescent sharks are also introduced to other Southeast Asia countries for food, especially Peninsular Malaysia, Singapore, Indonesia and Myanmar. In Malaysia, Singapore and Indonesia they are called ikan patin (which 'ikan' means fish in Malay and Indonesian), Malaysian Chinese prefer them steamed or cooked in whole, while Malay prefer cooking these fishes with Tempoyak and curry.{{cite web |title=Striped Catfish |url=https://www.iucnredlist.org/species/180689/7649971#geographic-range |website=IUCN Red List |date=19 January 2011}}

In Thailand, swai fish are commonly found in rivers and canals that run past important Buddhist temples or waterside places. Swai live in large schools, sometimes with other fish such as spot pangasius and red-tailed tinfoil with tinfoil barb. Fish that live in that area, people won't catch them, and often feed them (usually bread), which is considered a merit-making and fun activity.{{cite book|last= Uk-katawewa|first=Sompote|title=Interesting Facts about Thai Freshwater Fish, Volume 2|year=2004|publisher=Council Printing House|location=Bangkok|isbn=974-00-8738-8|page=31|language=thai}}

File:Swai fillet.jpg

Pangasius does not have a gourmet reputation and is sold cheaply as swai ({{IPAc-en|s|w|aɪ}}, from Thai สวาย s̄wāy){{Cite web| url= https://pantip.com/topic/30711852|title=ซื้อปลาSwai Fillets มา เอาไปทำไรกินได้บ้างคะ?|website=Pantip.com|language=thai}}{{Cite web| url= https://books.google.com/books?id=zBY_z6CkJEIC&q=swai+vietnamese|title= Status of the Mekong Pangasianodon Hypophthalmus Resources, with Special Reference to the Stock Shared Between Cambodia and Viet Nam|date=July 12, 2002| publisher= Mekong River Commission| via= Google Books}} in the United States, panga (or pangas) in Europe and cream dory and basa in several Asian countries and in Australia and the UK.

Despite its lowly reputation, the total export of pangasius from Vietnam reached US$1.8 billion in 2014.{{Cite web|title = Sector profile|url = http://seafood.vasep.com.vn/673/onecontent/sector-profile.htm|website = seafood.vasep.com.vn|access-date = 2016-02-15|first = Luu Viet|last = Thang}}

Pangasius fillets are an increasingly popular product because of their low cost, mild taste and firm texture. Recipes for other whitefish such as sole or halibut can be adapted to pangasius.{{Cite journal |url =http://vietfish.org/html/en/082012/082012.pdf |archive-url =https://web.archive.org/web/20160223095508/http://vietfish.org/html/en/082012/082012.pdf|url-status =usurped| archive-date =2016-02-23|title =The three key steps to restore the image of Pangasius|last = | publisher = VASEP| journal =Vietfish International|page =88}}

Pangasius is an omnivorous fish, and thus does not require a high level of animal protein in its diet. Typical grading sizes are {{cvt|3|–|5|oz|sigfig=2}}, {{cvt|5|–|7|oz|sigfig=2}}, and {{cvt|7|–|9|oz|sigfig=2}}.{{cite web |url=http://www.chefs-resources.com/Swai-Fish-Information-Recipes |title= Swai Fish Profile | website = Chefs-resources.com |access-date=2012-06-22}}

File: Pangasius in aquarium.jpg

While juvenile iridescent sharks are sold as pets for home aquariums, they are not easy fish to keep. Iridescent sharks are schooling fish that prefer groups, are accustomed to living in rivers, and are active fish that require space. They have very poor eyesight, so detected movement from outside of their habitat can be seen as a threat. If stressed, their first instinct is to flee; a blind dash can cause injury in an aquarium environment. These injuries may result in the fish sinking to the bottom, where it may lie on its side or back until it recovers.{{cite book |title=Exotic Tropical Fishes |last1= Axelrod |first1=Herbert R. |first2=Cliff W. |last2=Emmens |first3=Warren E. |last3=Burgess |first4=Neal |last4=Pronek |first5=G. |last5=Axelrod |publisher=T.F.H. Publications |year=1996 |isbn=0-87666-543-1}}

Iridescent sharks require a minimum tank size of {{convert|12|m|ft|abbr=on}} to develop naturally. Schools require even larger tanks. If given enough room and fed adequately, they can reach {{convert|1|m|ft|abbr=on}} in length. In most home aquaria, the lack of space stunts their growth. For this reason, most iridescent sharks kept in home aquaria grow to {{convert|15|to|30|cm|in|round=0.5|abbr=on}} in length only and may die prematurely. When provided adequately sized aquaria and proper husbandry, iridescent sharks may live into their teens and grow to full size.{{cite web |last1=Viacrucis |first1=Jose |title=Iridescent Sharks: A Guide |url=https://aqualandpetsplus.com/iridescent-sharks/ |website=Aqualand Pets |date=March 26, 2024}}

• List of freshwater aquarium fish species

{{Reflist}}

{{Wikispecies|Pangasius hypophthalmus}}

{{Commons|Pangasius hypophthalmus}}

• [http://www.planetcatfish.com/common/species.php?species_id=172 Planet Catfish]

{{Taxonbar|from=Q312296}}

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Category:Pangasiidae

Category:Fish of the Mekong Basin

Category:Fish of Cambodia

Category:Fish of Laos

Category:Fish of Thailand

Category:Fish of Vietnam

Category:Commercial fish

Category:Fish described in 1878

Category:Taxa named by Henri Émile Sauvage