Cryptocaryon

{{Short description|Genus of single-celled organisms}} {{Speciesbox | image = Cryptocaryon_irritans.jpg | image_alt = | image_caption = Image of the parasite | image2 = Cryptocaryan irritans.jpeg | image_alt2 = | image2_caption = Yellow tang with white spots characteristic of marine ich | genus = Cryptocaryon | parent_authority = Brown, 1951 | species = irritans | authority = Brown, 1951 }}

'''''Cryptocaryon irritans''''' is a species of ciliate that parasitizes marine fish, causing '''marine white spot disease''' or '''marine ich''' (pronounced ''ick'').<ref name="Noga2010"/><ref>{{Cite American Heritage Dictionary|ich}}</ref> It is one of the most common causes of disease in marine aquaria.

==Taxonomy== ''Cryptocaryon irritans'' was originally classified as ''Ichthyophthirius marinus'', but it is not closely related to the other species. It belongs to the class Prostomatea, but beyond that its placement is still uncertain.

==Clinical== The symptoms and life-cycle are generally similar to those of ''Ichthyophthirius'' in freshwater fish, including white spots, on account of which ''Cryptocaryon'' is usually called marine ich. However, ''Cryptocaryon'' can spend a much longer time encysted. Fish that are infected with Cryptocaryon may present with small white spots, nodules, or patches on their skin, fins, or gills. In some cases the parasite may attach on the gills of the fish, making it much harder to see.<ref name="humblefish-ich">{{cite web |last1=Miller |first1=Bobby |title=Marine Ich |url=https://humble.fish/community/threads/marine-ich.11/ |website=Humble Fish |publisher=Humble Fish |access-date=27 January 2026}}</ref> They may also have ragged fins, cloudy eyes, pale gills, increased mucus production, or changes in skin color, and they may appear thin. Behavioural changes may be observed, such as scratching, abnormal swimming, lethargy, hanging at the surface or bottom of the tank, or breathing rapidly as if in distress.<ref name="Yanong2009"/>

=== Life cycle === ''C. Irritans'' has a 4-stage lifecycle, consisting of a Trophon stage, a Protomont stage, a Tomont stage, and a Theront stage. The characteristic white spots occur in the Trophont stage, where ''C. irritans'' finds a host fish to attach to. This is where the paraste begins feeding on the host fish for 3-9 days. After this, ''C. irritans'' falls off the host and enters the Protomont stage. The free-swimming parasite now find substrate such as rocks or sand to attach to. Once it has achieved this, the parasite enters the Tomont stage and begins to reproduce asexually, this may last from 3 to 72 days. Lastly, the parasite enters the Theront stage, where it once again becomes free-swimming. Here, it searches for a new host to attach to and begins the cycle anew.<ref name="brs-ich">{{cite web |title=The Life Cycle of Marine Ich (Cryptocaryon irritans) |url=https://www.bulkreefsupply.com/content/post/md-2021-02-marine-ich-life-cycle-diagram-cryptocaryon-irritans-treatment |website=bulkreefsupply.com |publisher=Bulk Reef Supply |access-date=27 January 2026}}</ref> thumb|A diagram showing the lifecycle of Marine Ich (Cryptocaryon irritans) infecting a fish

=== Treatment === Due to this extensive life-cycle, Marine Ich can be difficult to treat. Especially as most available treatments are not safe for corals, snails and other invertebrates. This usually forces the aquarist to quarantine the infected fish in a separate tank for the duration of the treatment.<ref name="humblefish-ich"></ref>

Useful treatments (but not safe for reef tanks or invertebrates) of ''C. irritans'' include copper solutions, formalin solutions and quinine based drugs (such as chloroquine phosphate and quinine diphosphate) or hyposalinity (at 1.009 specific gravity). <ref>{{cite web |last1=Miller |first1=Bobby |title=Hyposalinity aka Osmotic Shock Therapy |url=https://humble.fish/community/threads/hyposalinity.22/ |website=humble.fish |publisher=Humble Fish |access-date=27 January 2026}}</ref>.

Another treatment option called the Tank Transfer Method involves moving the affected fish to another tank at specific times in the parasite's lifecycle, intending for the parasite to "drop off" the fish in a separate, quarantined tank and moving the fish back to its original tank before the parasite is able to reattach. <ref name="humblefish-ttm">{{cite web |last1=Miller |first1=Bobby |title=Tank Transfer Method (all versions) |url=https://humble.fish/community/threads/tank-transfer-method-all-versions.6800/ |website=Humble.fish |publisher=Humble Fish |access-date=27 January 2026}}</ref>

==== Ich management ==== Because ich can be extremely hard to eradicate in marine aquaria, so-called "Ich management" has become an alternative approach to dealing with this parasite. Rather than going through the time and labour intensive treatment or quarantine process, aquarists may choose to instead manage ich by allowing the fish to fight off the parasites on their own. Through a combination of a healthy, varied diet, and good water quality, the symptoms of ich may be minimal on the fish and may even be easier on the fish than moving it to a new environment in a quarantine tank. As marine ich is not always a deadly parasite, this method offers an alluring premise compared to the labour intensive ich-eradication strategy.<ref>{{cite web |title=Reef Tank Pest Eradication vs. Management Explained |url=https://www.bulkreefsupply.com/content/post/reef-tank-pest-eradication-vs-management-explained |website=bulkreefsupply.com |publisher=Bulk Reef Supply |access-date=27 January 2026}}</ref> Critics, such as Bobby Miller from Humble Fish, have warned against this method, saying "All it takes is one “stressor event” to undo years of ich management." indicating how delicate and precarious this approach is. <ref>{{cite web |last1=Miller |first1=Bobby |title=Ich eradication vs. Ich management |url=https://humble.fish/community/threads/ich-eradication-vs-ich-management.28/ |website=humble.fish |publisher=Humble Fish |access-date=27 January 2026}}</ref>

==See also== * Freshwater ich for the similar disease of freshwater fishes

==References== {{Reflist |refs= <ref name="Noga2010">{{cite book |url=https://books.google.com/books?id=zdXW8NjV3IQC&pg=PA135 |title=Fish Disease: Diagnosis and Treatment |publisher=Wiley-Blackwell |first=Edward J. |last=Noga |edition=2nd |pages=135–137 |year=2010 |isbn=978-0-8138-0697-6}}</ref>

<ref name="Yanong2009">{{cite web |url=http://edis.ifas.ufl.edu/fa164 |title=''Cryptocaryon irritans'' Infections (Marine White Spot Disease) in Fish |publisher=University of Florida |first=Roy P. E. |last=Yanong |year=2009}}</ref>

}}

==Further reading== * {{cite journal|last1=Colorni|first1=Angelo|title=Biology of ''Cryptocaryon irritans'' and strategies for its control|journal=Aquaculture|date=December 1987|volume=67|issue=1/2|pages=236–237|doi=10.1016/0044-8486(87)90041-X|bibcode=1987Aquac..67..236C }} * {{cite journal|last1=Dickerson|first1=Harry W.|title=Treatment of ''Cryptocaryon irritans'' in Aquaria|journal=SeaScope|date=Summer 1994|volume=11}} * {{cite journal|last1=Diggles|first1=B. K.|last2=Lester|first2=R. J. G.|title=Infections of ''Cryptocaryon irritans'' on wild fish from southeast Queensland, Australia|journal=Diseases of Aquatic Organisms|date=June 1996|volume=25|issue=3|pages=159–167|doi=10.3354/dao025159|doi-access=free}} * {{cite journal|last1=Goto|first1=Tsuyoshi|last2=Hirazawa|first2=Noritaka|last3=Takaishi|first3=Yoshihisa|last4=Kashiwada|first4=Yoshiki|title=Antiparasitic effects of ''Sophora flavescens'' root extracts on the ciliate, ''Cryptocaryon irritans''|journal=Aquaculture|date=16 September 2014|volume=435|pages=173–177|doi=10.1016/j.aquaculture.2014.09.007}} * {{cite journal|last1=Li|first1=Ruijun|last2=Dan|first2=Xueming|last3=Li|first3=Anxing|title=''Siganus oramin'' recombinant L-amino acid oxidase is lethal to ''Cryptocaryon irritans''|journal=Fish & Shellfish Immunology|date=December 2013|volume=35|issue=6|pages=1867–1873|doi=10.1016/j.fsi.2013.09.026|pmid=24113573|bibcode=2013FSI....35.1867L }} * {{cite journal|last1=Lin|first1=Qianqian|last2=Yang|first2=Mei|last3=Huang|first3=Zhen|last4=Ni|first4=Wei|last5=Fu|first5=Guoliang|last6=Guo|first6=Guowei|last7=Wang|first7=Zhengchao|last8=Huang|first8=Xiaohong|title=Cloning, expression and molecular characterization of a 14-3-3 gene from a parasitic ciliate, ''Cryptocaryon irritans''|journal=Veterinary Parasitology|date=8 November 2013|volume=197|issue=3–4|pages=427–435|doi=10.1016/j.vetpar.2013.07.028|pmid=23932453}} * {{cite journal|last1=Yin|first1=Fei|last2=Gong|first2=Qiyang|last3=Li|first3=Yanwei|title=Effects of ''Cryptocaryon irritans'' infection on the survival, feeding, respiratory rate and ionic regulation of the marbled rockfish ''Sebastiscus marmoratus''|journal=Parasitology|date=February 2014|volume=141|issue=2|pages=279–286|doi=10.1017/S0031182013001613|pmid=24139291|s2cid=22057733 }}

==External links== *[http://www.masa.asn.au/masawiki/index.php/Cryptocaryon ''Cryptocaryon'']

Category:Intramacronucleata Category:Ciliate genera Category:Fish diseases Category:Veterinary protozoology Category:Monotypic eukaryote genera