Ich Discussion between NeuroDoc and Steve-S

[NeuroDoc]

This thread is started as a continuation of a previous thread in which Steve and I butted heads with regards to ich (Cryptocaryon irritans). Hopefully we will all learn something.

Let's start with information I think we can agree upon - the life cycle of ich. I will outline it as I understand it, and you can correct me where you think I am in error. Here goes.

 

[steve-s]

Cheers
Steve

 

[Curtswearing]

I'm going to make up stuff and disagree with both of you just for fun.

 

[NeuroDoc]

The Life Cycle of Ich

Steve, here is the life cycle of ich, as I understand it. Please make any corrections. My sources are listed at the bottom.

Overview:
trophont->protomont->tomont->tomites->theront->trophont

Details:
trophont: the stage that infects fish. Burrows into epithelium (outer skin later) of the fish, where it matures. Maturitation may be as short as 3 days, and as long as 7, but not longer, with the peak being 4-5 days. When the trophont is mature it drops off the fish to form the protomont.

protomont:formed when the trophont exits the host and sheds its cilia. Exists for 2-8 hours free moving until it attaches to substrate (not another fish).

tomont: once attached to substrate the protomont encysts to form the tomont. It is this stage of the parasites life that is most variable. Depending on temperature, tomonts mature in 3-72 days. At common reef temperatures the tomont typically matures in 3-8 days, with the peak being 4-8. It is this stage that is susceptible to desctruction by hyposalinity.

tomites: as the tomont matures it creates daughter cells within its cyst. It is these daughter cells that are called tomites. 200-1000 are produced within each tomont.

theronts:when the tomont matures, it releases the tomites, at which point they are called theronts. This is the free-floating, infectious stage of the parasite. Depending on conditions, these may live for 12-48 hours looking for a host, but become less infectious as time passes. Also susceptible to death by hyposalinity.

Terry Bartelme states that the complete life cycle is usually 1-2 weeks in a typical home aquarium.

sources:
News from the Warfront with Cryptocaryon irritans by Terry Bartelme (part 2 of 5) (also printed in Advanced Aquarist, beginning in Nov 2003)
Saltwater Ich (Cryptocaryon) Life Cycle
Ich in Saltwater Fish Veterinary & Aquatic Services Department, Drs. Foster & Smith, Inc.
Marine Ich/Cryptocaryon irritans - A Discussion of this Parasite and the Treatment Options Available, Parts I&II by Steven Pro

 

[NeuroDoc]

I'm going to make up stuff and disagree with both of you just for fun.

Beware, we both can get pretty nasty. :badgrin:

 

[mower7]

One question I had was, what is a "fish". What I mean is what type of fish
do Ick live "on/in".

For example, is a cleaner shrimp suseptable to ick or is it only the scaled type fish ? (Sorry I don't know the scientific names for the different families of fish).

The reason I ask is that I have a reef that was infected with Ick, so i pulled all the "fish" out of the tank and put them in to QT, where I lowered the salinity to 1.0009. But I read that the invertibrates (shrimp) can't handle the low salt, so they stayed in the display tank (with the rest of the corals). IS this the correct method ? And will my display tank be free from Ick after ?? 5 weeks ? (it seems that your earlier post suggest that it only takes 2 weeks a 75-80 F temps, am I reading that correctly ?).

 

[Curtswearing]

Actually, I'm looking forward to the information.

 

[Brenden]

Saw the other thread so I am glad you did this NeuroDoc. Steve-S IMO is the best at this so we all have a opportunity to learn something from this.

 

[Brenden]

One question I had was, what is a "fish". What I mean is what type of fish
do Ick live "on/in".

For example, is a cleaner shrimp suseptable to ick or is it only the scaled type fish ?

Any fish is susceptible. Inverts like shrimp, crabs, corals etc do not host it. However anything wet can transfer it to your tank.

When your fish are in a QT going through hypo the main needs to stay fallow 6-8 weeks to rid the tank of ich.

 

[NeuroDoc]

Any fish is susceptible. Inverts like shrimp, crabs, corals etc do not host it. However anything wet can transfer it to your tank.

When your fish are in a QT going through hypo the main needs to stay fallow 6-8 weeks to rid the tank of ich.

Brenden is correct. Any fish can be a host, although Bartelme states "Elasmobranches such as sharks and rayfish are considered to be naturally resistant."

Anything wet can transfer the tomont stage of the parasite. It is possible that the tomont attaches itself to the shell of a clam, snail, crab, shrimp, etc.., as well as rocks and corals.

 

[NeuroDoc]

The reason I ask is that I have a reef that was infected with Ick, so i pulled all the "fish" out of the tank and put them in to QT, where I lowered the salinity to 1.0009. But I read that the invertibrates (shrimp) can't handle the low salt, so they stayed in the display tank (with the rest of the corals). IS this the correct method ? And will my display tank be free from Ick after ?? 5 weeks ? (it seems that your earlier post suggest that it only takes 2 weeks a 75-80 F temps, am I reading that correctly ?).

Be patient, we are going to get to this point in the discussion. It was a topic of debate in our previous thread. But the short answer is no, not if you want to be certain it is gone.

 

[steve-s]

Steve, here is the life cycle of ich, as I understand it. Please make any corrections. My sources are listed at the bottom.

Essentially correct with a few very minor corrections.

Protomont: Just under a day, 12-18 hrs

Tomont: Hyposalinity reduces the viability of the tomites. It doesn't act destroy the tomont. It's why it takes a few life cycles before marked results are evident. It's actually Dr Colorni's contension that the prolonged exposure to low salinity is what affects the tomite and protomont and not so much the tomont itself. It's rapid drops in salinity that affect it's ability to cell divide.

Tomite: The number that excyst the tomont are usually 200 or less, rarely close to 300.

The life cycle duration will greatly vary on activity level/change within the system but is primarily driven by temperature. The average that Terry speaks of is an accurate one but I am find much closer to one week than two. More and more hobbyists are keeping there tanks in the 80+ area.

Cheers
Steve

 

[steve-s]

Brenden is correct. Any fish can be a host, although Bartelme states "Elasmobranches such as sharks and rayfish are considered to be naturally resistant."

Naturally resistant yes but not immune. The anything wet rule still applies!! Sharks and rays can still become infested.

Be patient, we are going to get to this point in the discussion. It was a topic of debate in our previous thread. But the short answer is no, not if you want to be certain it is gone.

Agreed, let's let this discussion progress easily. Any unanswered or missed question opportunities can be answered afterwards.

For everyone, if there's an immediate need, start a new thread...
http://www.reeffrontiers.com/forums/forumdisplay.php?f=15
Mower7 specifically. Never trust 4-5 weeks fallow for an infested tank. 6 at the very minimum but preferabley 8. The hypo + observation time afterwards (2 weeks) will take that long anyway.

Cheers
Steve

 

[NeuroDoc]

Steve, as you know from our previous discussion, I am very interested in sources. Can you provide any for the data you present?

 

[steve-s]

http://petsforum.com/personal/trevor-jones/marineich.html
http://www.breedersregistry.org/Reprints/SeaScope/v11_sumr/crypto.htm
http://www.reefs.org/library/aquarium_net/0297/0297_2.html
http://www.springerlink.com/content/wc3k1ldy8t8y/
http://www.ocean.org.il/Eng/Researchers/page_angelo.asp
http://www.cvm.ncsu.edu/docs/edward_noga.html

Dr Noga will actually suggest you talk directly Dr Colorni.

That's a good place to start I guess. Most others are abstracts that require paisd access. Most say the same thing and aren't worth it.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed

Cheers
Steve

 

[moortim]

Just tagging along, very interesting stuff.

 

[NeuroDoc]

http://petsforum.com/personal/trevor-jones/marineich.html
http://www.breedersregistry.org/Reprints/SeaScope/v11_sumr/crypto.htm
http://www.reefs.org/library/aquarium_net/0297/0297_2.html
http://www.springerlink.com/content/wc3k1ldy8t8y/
http://www.ocean.org.il/Eng/Researchers/page_angelo.asp
http://www.cvm.ncsu.edu/docs/edward_noga.html

Dr Noga will actually suggest you talk directly Dr Colorni.

That's a good place to start I guess. Most others are abstracts that require paisd access. Most say the same thing and aren't worth it.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed

Cheers
Steve

Fantastic! Thank you. The first one you mention is a great overview and summary of sources. I can access a lot of the scientific journals with electronic access through my medical school's library. The Colorini and Burgess article (4th link) looks good, too. I have only had time to scan it, but I have downloaded the pdf and will read it later. If you, as moderator, can give me more storage space for attachments, I could even post it here (I'll have to check on the copyright issues first).

I have no problems with the minor changes, although I need to read some more to feel 100% comfortable with the effects of hyposalinity on the tomont/trophont, but it isn't a show-stopper.

 

[NeuroDoc]

Now that we have agreed to the basics of the life-cycle. My next question is one we couldn't agree upon. To what extent does C. irritans exist in the wild?

Also for this question and future discussion, a term I used frequenty in our previous discussion was subclinical. Let me define it so that we are using it in the same manner.

subclinical: Denoting the presence of a disease without manifest symptoms; may be an early stage in the evolution of a disease.

 

[NeuroDoc]

As an answer to this question, I have stated that this is a fairly significant number.

[begin lecture]Previously I based this on my understanding of general parasitology. Remember that the goal of parasites in general is to reproduce, and in fact, to maximize reproduction. Reproduction is limited if the host dies, which is why most parasites do not kill their obligate hosts. Parasites also go extinct if there is a small number of hosts; this doesn't allow them to create enough "children" to ensure that a new host is infected. It's all about numbers and probabilities. (all of this applies to life in the wild, and not in an enclosed system we call an aquarium.[end of lecture]

Now let me offer a source (for which I only currently have the abstract, my electronic access doesn't get me the full text for this article).

Diggles, B.K. & Lester, J.G. “Infections of Cryptocaryon irritans on Wild Fish from Southeast Queenland, Australia.” Diseases of Aquatic Organisms, 25(3), 159-167, 1996c.

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-1. At Site 2, a coastal bar area, the prevalence of infection dropped to 66% and a mean intensity of 5.0 parasites fish-1, whilst at Site 3 on the Great Barrier Reef, prevalence was lowest at 51% with a mean intensity of 2.3 parasites fish-1. 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-1, whilst at Site 2 (n = 74) the prevalence was 88% at a mean intensity of 5.2 parasites fish-1. 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-1. The diameter of the tomonts collected from A. australis from Sites 1 and 2 varied inversely with water temperature, and was not related to host size. Our results show that infections of C. irritans 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. irritans may 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 realize that this isn't a wide sampling of fish species, and the authors admit that their study is limited in that way. However, a range of 38% to 100% prevalance in wild-caught fish certainly leads them to conclude that this parasite is common on wild fish. Particularly given that 2/3 of all fish caught showed infection. I would argue that based upon general principles, this finding likely holds across species and geographic areas.

I also don't know if the tomonts were visible to the naked eye, but based upon what they say I don't think so. I think that these represent sub-clinical infections.

 

[steve-s]

You will need to PM MtnDewMan about the storage space but I seriously doubt you can post the full articles without violating copyright. They would be freely accessible otherwise I would think?

I am glad you made reference to wild vs enclosed, that was one point of contention earlier that I don't think you fully took into account. In an enclosed system the goals of the parasite remains the same, the outcome of the host is often death. In the wild your statement have been correct for the majority.

I would be very interested in the full read but this is only one area of the ocean. Without at least one or two more samplings from different oceans, I think it's a bit of a leap to say they would all be the same (this finding likely holds across species and geographic areas). If you look at the dramatic drop in the rate of infection the further out they went (79-51%), I think where may make a fair difference in the findings.

There is also lack of species identification for the 13-14 tested (except for the Breams), fish densities in the test areas, how the specimens where collected and held while awaiting testing, how testing was carried out to confirm the presence of C. irritans or just a parasite and so on. There is actually quite a bit of information missing that the full article may or may not clear up.

I am by no means trying to poke as many holes as I can find here. More just trying to point out that this would be only a "sampling" of what might be possible. Without more concrete evidence and an actual accounting of the process in which this was carried out, I don't think any conclusions can be made. The Breams mentioned in the abstract are primarily schooling fish that inhabit estuaries and costal waters. The fish we keep do not fall into that "grouping" so to speak.

You have definately shown there to be strong supporting evidence, I hope the full article may lead to a more concerte conclusions. Since I do not have the same access to these types of articles, I hope your search does not end solely with this one article/abstract.

Cheers
Steve