Cryptocaryon (Marine Ich) in Public Aquaria

How Do You Manage Marine Ich in Public Aquaria?

Cryptocaryon irritans (Marine Ich)

Cryptocaryon Life Cycle (photo credit University of Florida Extension Service)

Cryptocaryon irritans is the marine species of the aquarium disease commonly known as “Ich.”  In the freshwater world Ichthyopthirius multifilis plagues small aquarium owners if quarantine and management aren’t done properly.  The good news is that it’s fairly easy to rid a small home aquarium from this pest if you know what you are doing.

In large public aquaria with Marine Ich it’s a whole ‘nuther story.  Large marine aquaria frequently bring in wild caught individuals that aren’t bred in captivity and trade species between facilities.  Even though they may do a good job of quarantine it’s almost inevitable that Cryptocaryon will make it into their system at some point in time.  Because these facilities usually run off of common filtration systems once it’s there, it is a nightmare to eliminate.  This disease infects the eyes, skin, and gills, so not only is it an aesthetic problem, but a potentially major health problem.  Ich can result in large numbers of death if treatment is not started in a timely manner.



Quarantine ideally for 12 weeks.  This can be difficult in a public facility where space is limited, especially on larger species of fish. 30 days of quarantine will reveal  many but not all Cyptocaryon infections.

UV Sterilization and Ozonation of Water

UV sterilization will only kill free floating forms of this disease and thusly isn’t that affective in preventing outbreaks. Ozonation is very effective but can significantly affect water quality especially in a salt water environment. Both of these types of systems are also costly for facilities of this size.

Challenges in Treatment

Life Cycle

  • The life cycle of this parasite varies due to many factors including water chemistry, temperature, strain of organism, and species of fish on exhibit.  It can vary from a few weeks to a few months.
  • There is a stage of the life cycle where this parasite encysts and exists in the environment.  This presents a significant challenge because this stage is hard to kill and even if you removed all fish off exhibit (nearly impossible in a large facility) and rid them of the disease, they would be reinfected on reintroduction to their exhibit.

Treatment Choices

Copper Sulfate

Treatment time 4-6 weeks


  • Very Effective


  • Elasmobranchs (sharks and rays) and invertebrates (corals, shrimps, lobsters, etc) are sensitive and may die when exposed.
  • Can cause respiratory distress resulting in the need for Methylene Blue treatment.  Blue tinted water is a turn off for aquarium visitors.


Treatment time 2-4 weeks


  • Safe for Elasmobranchs


  • Not as effective as Copper
  • Requires frequent retreatment

Malachite Green


  • Safe for invertebrates


  • Not as effective.
  • Requires frequent retreatment
  • Green tank water is a turn off for aquarium visitors.

Increased Habitat Temperature


  • Can be combined with other treatments
  • Somewhat simple to do


  • Species sensitivities in the large numbers of marine fishes potentially found in a public marine aquarium

What have you found to be effective for managing Marine Ich in a large Public Aquarium?

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