Ich/velvet in mandarin.

[MnFish1]

The idea that a specific gravity of 1.020 somehow helps control Cryptocaryon outbreaks is not borne out in real life. 1.020 only serves to save stores money on salt, and help reduce osmotic stress in fish with damaged skin. It can actually increase the incidence of Uronema and Amyloodinium (at least 1.020 is smack within the preferred range for those two species)

There is a paper that indicates that the prevalence of Cryptocaryon in wild caught fish was highest at the mouth of an estuary, and lowest out on the Great Barrier reef itself. The paper also shows why newly collected wild caught fish must be treated prophylactically.

Infections of Cryptocaryon irritans on wild fish from southeast Queensland, Australia
B. K. Diggles, R. J. G. Lester

ABSTRACT: Wild-caught marine fish from 3 sites in SE Queensland, Australia, were examined over a
period of up to 13 mo for infections of the parasitic ciliate Cryptocaryon irritans. Infections of C. irritans
were found to be common on the fish sampled. Out of a total of 358 fish (14 species), 239 (66.7%) from
13 species were found to be infected. At Site 1 at the mouth of an estuary, the prevalence of C. irritans
infections was 79% and the mean intensity was 12.9 parasites fish-'. At Site 2, a coastal bar area, the
prevalence of infection dropped to 66 % and a mean intensity of 5.0 parasites fish-', whilst at Site 3 on
the Great Barrier Reef, prevalence was lowest at 51 % with a mean intensity of 2.3 parasites fish-' The
study concentrated on 2 sparid fishes, Acanthopagrus australis from Sites 1 and 2 and Gymnocranius
audleyi from Site 3. The prevalence of infections on A. australis from Site 1 (n = 101) was 100% with a
mean intensity of 14.6 parasites fish-', whilst at Site 2 (n = 74) the prevalence was 88 % at a mean intensity
of 5.2 parasites fish-'. There was no apparent seasonality In prevalence or intensity of infections at
Sites 1 and 2 despite water temperatures ranging between 15 and 27°C. At Site 3, the prevalence of
infections of G. audleyi (n = 39) was 38% with a mean intensity of 1.9 parasites fish-'. The diameter of
the tomonts collected from A. australis from Sites 1 and 2 vaned inversely with water temperature, and
was not related to host size. Our results show that infections of C vntans are common on wild fish, not
rare as previously thought. This may be partially due to the increased sensitivity of our tomont collection
technique. Our data suggest that C. irritansmay exhibit a degree of host specificity in the wild, and
also that its natural distribution can be extended into estuaries and seasonally into warm temperate
waters.

I think this is also borne out by the seasonal studies from Vietnam.

 

[Jay Hemdal Verified Community Expert]

I think this is also borne out by the seasonal studies from Vietnam.

Do you have the titles for those? I don’t think I have them in my files.

Side note: on Reef Central, they called it “Crypto”. For obvious reasons, that name doesn’t work well today (grin). I used to shorthand it as “Crypt”. Aquatic vets sometimes use “CI”, but I think that’s too obtuse. When I came here, everyone called it “Ich” so I just followed suit for clarity. We do have some ability to “steer this ship” - I’ll bring it up to the fish medics.

 

[MnFish1]

Do you have the titles for those? I don’t think I have them in my files.

Side note: on Reef Central, they called it “Crypto”. For obvious reasons, that name doesn’t work well today (grin). I used to shorthand it as “Crypt”. Aquatic vets sometimes use “CI”, but I think that’s too obtuse. When I came here, everyone called it “Ich” so I just followed suit for clarity. We do have some ability to “steer this ship” - I’ll bring it up to the fish medics.

I will post the links here (assuming I can)

 

[MnFish1]

https://iopscience.iop.org/article/...s,ornamental fish in Vietnam is very limited.This is an interesting one:
https://pubmed.ncbi.nlm.nih.gov/399...ility,; Lutjanidae; marine teleost pathology.@mcarroll

 

[MnFish1]

https://iopscience.iop.org/article/...rnamental fishes are receiving an,Although C.
https://www.researchgate.net/public...s_in_wild_marine_ornamental_fish_from_Vietnam

 

[mcarroll]

https://iopscience.iop.org/article/...s,ornamental fish in Vietnam is very limited.This is an interesting one:
https://pubmed.ncbi.nlm.nih.gov/399...ility,; Lutjanidae; marine teleost pathology.@mcarroll

Intriguing, but the meat of it is paywalled – all sizzle, no steak! ;)

If you have access, can you share...or summarize beyond what's in the Abstract?

What conclusions (if any) were you able to draw from the article?

This study outlines the challenges of managing a Ci outbreak in quarantine under unprecedented environmental conditions, underscores the importance of species-specific management strategies and provides detailed insights into host–pathogen interactions and treatment responses.

Every one of those points needs illuminating – eg. what do they mean by "unprecedented environmental conditions"??? – a very unsatisfying place to leave things! LOL.

https://iopscience.iop.org/article/...rnamental fishes are receiving an,Although C.
https://www.researchgate.net/public...s_in_wild_marine_ornamental_fish_from_Vietnam

Very interesting that Summer collections should net (pun!) fish that are almost 100% healthy (from Crypo, at least), according to this...

The development of the parasite was significantly damaged at the temperature above
31ºC and no parasite was recovered from any fish reared at 34ºC.

That's 87.8ºf and 93.2ºF, respectively.

(I'm guessing that data like this is where the general advice to raise temperatures in QT comes from?)

They note similar trends for Ich in freshwater fish.

Would be great if they had data like this from a longer time frame – they could potentially predict which fish to keep grouped/which fish not to mix together after collection.

They observe that the infection rates they saw were almost the same as past reports as well as reports on freshwater Ich.

If collecting is done in Spring, then Collectors and Wholesalers are both crazy....infection rates are off the charts. Summer is the only safe season, Winter is marginal.

I'm guessing year-round demand makes it difficult, but limiting collections to the warmest times of the year ought to make a difference, according to this data.

I'll have to give this a re-read later.

 

[mcarroll]

@Australian_Reef you can ask us to go set up our own thread any time you want.....we're not off topic, but we're not really on topic either. ;)

 

[Jay Hemdal Verified Community Expert]

Intriguing, but the meat of it is paywalled – all sizzle, no steak! ;)

If you have access, can you share...or summarize beyond what's in the Abstract?

What conclusions (if any) were you able to draw from the article?


Every one of those points needs illuminating – eg. what do they mean by "unprecedented environmental conditions"??? – a very unsatisfying place to leave things! LOL.


Very interesting that Summer collections should net (pun!) fish that are almost 100% healthy (from Crypo, at least), according to this...


That's 87.8ºf and 93.2ºF, respectively.

(I'm guessing that data like this is where the general advice to raise temperatures in QT comes from?)

They note similar trends for Ich in freshwater fish.

Would be great if they had data like this from a longer time frame – they could potentially predict which fish to keep grouped/which fish not to mix together after collection.

They observe that the infection rates they saw were almost the same as past reports as well as reports on freshwater Ich.

If collecting is done in Spring, then Collectors and Wholesalers are both crazy....infection rates are off the charts. Summer is the only safe season, Winter is marginal.

I'm guessing year-round demand makes it difficult, but limiting collections to the warmest times of the year ought to make a difference, according to this data.

I'll have to give this a re-read later.

Weird - it wasn’t behind a paywall for me. Maybe I have a Research Gate access, but I could see the article on my main computer and my phone.

 

[mcarroll]

Weird - it wasn’t behind a paywall for me. Maybe I have a Research Gate access, but I could see the article on my main computer and my phone.

Gotta hit the "Radware" link and not the article link......got it now.

 

[mcarroll]

Actually both "Radware" links seem to go to "The Prevalence..." article, I don't get to "An Outbreak..." from either one...unless I'm hallucinating. :D

I will take the title to Google Scholar and I'm sure it'll show that way, but if the links are boogered, you can fix em if you want.

 

[Australian_Reef]

@Australian_Reef you can ask us to go set up our own thread any time you want.....we're not off topic, but we're not really on topic either. ;)

No please carry on. It’s interesting.
I would like to know how you personally QT and introduce fish into your system though.

 

[mcarroll]

https://iopscience.iop.org/article/...s,ornamental fish in Vietnam is very limited.This is an interesting one:
https://pubmed.ncbi.nlm.nih.gov/399...ility,; Lutjanidae; marine teleost pathology.@mcarroll

OK...confirmed both "Radware" links are to the same article, AND neither I nor Google Scholar can find a PDF of this article:

"An Outbreak of Cryptocaryon irritans in Aquarium Quarantine..."​

 

[Jay Hemdal Verified Community Expert]

OK...confirmed both "Radware" links are to the same article, AND neither I nor Google Scholar can find a PDF of this article:

"An Outbreak of Cryptocaryon irritans in Aquarium Quarantine..."​

That’s a Wiley paper, those are never free unless you have academic access. There is a link a few pages in, where you can buy a day’s access for $16. Personally, I’d skip it - in the abstract, they said that the case started at a public aquarium where they lost 450+ fish to crypt. Right there, that tells me they are not off to a good start, that should never have happened. Like an auto mechanic who doesn’t know enough to add oil to a car, burns up the engine, then makes a YouTube on how to rebuild car engines (grin).

 

[mcarroll]

That’s a Wiley paper, those are never free unless you have academic access. There is a link a few pages in, where you can buy a day’s access for $16. Personally, I’d skip it - in the abstract, they said that the case started at a public aquarium where they lost 450+ fish to crypt. Right there, that tells me they are not off to a good start, that should never have happened. Like an auto mechanic who doesn’t know enough to add oil to a car, burns up the engine, then makes a YouTube on how to rebuild car engines (grin).

Yeah, will have to let it go, but I admit I'm curious what they meant by "unprecedented conditions"?

 

[MnFish1]

OK...confirmed both "Radware" links are to the same article, AND neither I nor Google Scholar can find a PDF of this article:

"An Outbreak of Cryptocaryon irritans in Aquarium Quarantine..."​

One of the most interesting things is: "An outbreak of Cryptocaryon irritans (Ci) occurred during the quarantine of marine teleost fish at a large aquarium facility, leading to 457 mortalities across 16 species. " Kind of goes against the idea that ich is not a fatal disease/something to worry about

 

[MnFish1]

That’s a Wiley paper, those are never free unless you have academic access. There is a link a few pages in, where you can buy a day’s access for $16. Personally, I’d skip it - in the abstract, they said that the case started at a public aquarium where they lost 450+ fish to crypt. Right there, that tells me they are not off to a good start, that should never have happened. Like an auto mechanic who doesn’t know enough to add oil to a car, burns up the engine, then makes a YouTube on how to rebuild car engines (grin).

Did you see the wild Vietnam study?

 

[Jay Hemdal Verified Community Expert]

Did you see the wild Vietnam study?

I looked at it briefly - it seemed to correlate with the results in Diggle's paper. However, there was one major flaw in this paper. I can read between the lines that they acquired fish from a commercial supplier. I did NOT see how the fish were handled prior to collection, only after they received them. It is very likely that the study fish were housed in consolidation tanks prior to being sent out for the study.

 

[MnFish1]

I looked at it briefly - it seemed to correlate with the results in Diggle's paper. However, there was one major flaw in this paper. I can read between the lines that they acquired fish from a commercial supplier. I did NOT see how the fish were handled prior to collection, only after they received them. It is very likely that the study fish were housed in consolidation tanks prior to being sent out for the study.

I didn't get that impression - maybe we're talking about a different study. it was my impression that they randomly sampled fish in a given area during different season - and found seasonal differences - in which there was very little cryptocaryon found in season x and y (I don't remember) - and 70-80 percent in the other seasons. There were also differences between species that were fairly marked.

 

[MnFish1]

By the way this is the AI conclusion from the study - I cannot get into it myself anymore:
Prevalence in ornamental fish
A 2018 study of wild-caught ornamental fish from coastal areas near Nha Trang and Ha Long revealed a high prevalence of Cryptocaryon irritans:

• Overall infection rate: Out of 211 marine fish representing 15 species, 143 (67.7%) were infected.
• Seasonal variation: Prevalence was significantly higher during the spring (91.03% on average) compared to the summer (39.29%).
• Species-specific differences: Some species, like Platax teira and Paracanthurus hepatus, showed a 100% infection rate, while others, such as Rhinecanthus aculeatus, were infected at a much lower rate.

Risks in aquaculture

• Widespread distribution: Cryptocaryon irritans is a serious threat to both mariculture and aquariums in tropical and subtropical regions.
• Economic losses: In China, frequent outbreaks of C. irritans cause an estimated $100 million in economic losses annually. While specific financial impacts for Vietnam are not fully quantified, outbreaks can cause severe mortality and significant losses.
• Management challenges: Common chemical treatments are not effective in open environments like cages and ponds, though new control methods are being developed. High fish density and stress can trigger mass outbreaks in commercial nurseries.

Symptoms and effects
Infected fish may display several symptoms, though the extent of the pathology varies by the parasite strain, fish species, and water temperature. Symptoms include:

• Small white spots, nodules, or patches on the fins, skin, or gills
• Ragged fins, cloudy eyes, and pale gills
• Increased mucus production
• Changes in skin color
• Abnormal behavior, such as flashing (scratching), lethargy, or rapid breathing

 

[mcarroll]

One of the most interesting things is: "An outbreak of Cryptocaryon irritans (Ci) occurred during the quarantine of marine teleost fish at a large aquarium facility, leading to 457 mortalities across 16 species. " Kind of goes against the idea that ich is not a fatal disease/something to worry about

Can't disagree.

But the fact that Crypto sucks hardly seems worth publishing in 2025. "No – it really sucks!" Duh!

That makes me wonder what they meant by their comment about the circumstances. Outbreaks are normal – so what made theirs exceptional? Seems like there has to be more to the story.

Like a good movie trailer, they leave you wanting to pay the price of admission...who can blame them I guess? ;)