Ich ...

[Jabba]

OK I have become a tad tired of all the conflicting information about Ich and if it is present all the time or not.

I will add my two penneth here based on such conflicts and invite a debate based on evidence and facts to try to get to the bottom of it.

The Myth - Ich is always Present in all tanks - or is it a myth?

There are those that say Ich can live in a tank permanently and yet this article >> Ich Article 1 is pretty clear and has evidence from a phD student that Ich has no dormant cycle - end of story, period - if this is true then it CANNOT live in your tank permanently.

There are those who seem to indicate that it CAN live in the tank and although not explicitly stated this article >> Ich Article 2 seems to hint that it can.

Because not all the organisms are dead, they will bounce back in a few weeks or months

Move fish to a clean tank after 7 days. This reduces reinfection by tomites left behind after the initial treatments

How can this be? The previous article by the Ph.D (Dr Peter Burgess - Practical Fishkeeping) clearly states

The tomites'/theronts' metabolism is also temperature-dependent, but they must find a host within a very few days or perish: at 68oF none survived after 55 hours, according to Schaperclaus

as do other sites and some books state that the free swimming tomite cannot live indefinately without a host and it is this stage anyway that is vulnerable to medication.

Does this mean that although there are no white spots that our fish permanently have Ich just in varying degrees?

I refer to many books although I cannot remember a title or location that state that ich will appear if the fish gets stressed - this also implies that it is permanently present - so how can this be?

Surely if we take it to the logical conclusion and treat for 16 days as Ich Article 2 suggests then there can be no ich left ....

Something is missing from this puzzle - I'd be grateful if somebody could fill the gap - please no more myth or speculation, lets see the evidence so we can judge for ourselves.

I am not convinced by any particular argument yet.

 

[annka5]

"Itch is always present in all tanks"

This would mean by extension that no tank could exist in which there was no itch.

This is not true (even if to avoid daftness, we amend that to "itch is always present in fish tanks populated with tropical freshwater fish" !). I have never heard anyone coming up with a convincing argument that there is a theoretical difficulty to create a tank which has no itch in it, simply by adding only itch-free items.

To my mind: it's a myth, but what COULD (possibly - I couldn't prove it!) be said is that "low level populations of itch parasites are fairly commonplace and may not be apparant in the tank for months or years".

 

[Jabba]

low level populations of itch parasites are fairly commonplace and may not be apparant in the tank for months or years".

This is the dilemna, there seems to be no verifiable scientific proof for this theory, if Ich cannot have a dormant state then the only place it can perpetuate is on the fish, if it doesn't survive ont he fish but has no dormant state then how can it survive even in small numbers for periods that exceed its lifecycle, were it able to then this means our fish permanently have Ich, scientifically I can find no proof for this position either, and if conversly it can be shown to have a dormant state how would it know the best time to wake up.

All I can find research wise is people simply repeating what they have read or heard from others, there is little supporting biological or other evidence to support either position, unfortunately I haven't the necessary knowledge or time to do such a study.

 

[Bignose]

Jabba, all I can tell you is that none of the scientific research has ever mentioned a dormant stage. For example, a pretty recent paper, "Ichthyophthirius multifiliis Fouquet and ichthyophthiriosis in freshwater teleosts" by R.A. Matthews, in ADVANCES IN PARASITOLOGY Vol 59, 2005, is a review paper about Ich. A review paper means that it reviews all of the known scientific literature concerning ich, and collects all the research on ich in on paper and writes up a summary. it's not exactly short -- there's a lot of information about ich -- it is over 80 pages long. It references 289 other papers. In short, it contains everything important about ich that has ever been published in the scientific literature -- and it does not mention a dormant stage whatsoever. If I do a search in Web of Science (a database of scientific papers) for "Ichthyophthirius and dorm*" there are no results. If some researcher had ever discovered a dormant stage in ich's lifecycle, either that review paper or some other paper would have mentioned it.

At this point, there are two choices, then. That a so-far unstudied or undiscovered strain of ich does have a dormant stage, or that one doesn't exist and the the myth has been perpetuated for all the classical reasons. I think that since all of the scientific literature has no mention of any strain of ich (and there are many different strains) has ever mentioned a dormant stage, that the logical choice is to believe that one does not exist.

Could one exist? Absolutely, but I think that the chances that it hasn't been discovered yet are awfully slim. Ich is an important disease to make sure that farm fish don't catch since many of the treatments for ich make the fish unsafe to consume. Just to note how much it has been studied, again the 289 cited papers above. There has been and still is a lot of work being done on ich.

But, all of the reasons the myth keeps breathing are good. The confusion with the marine ich-like disease crypto that does have a dormant stage. The fact that fish can be asymptomatic carriers for a pretty long period of time -- not months most likely, but definitely weeks. And, because a fish can be asymptomatic, and look healthy and therefore its quarantine is cut short or nonexistant, as a low level carrier it takes a long time before the population of ich grows large enough to infect an entire tank. At colder temperatues, the lifecycle of ich is much longer than at tropical temperatures. At tropical temps, the lifecycle is 3 to 5 days, but at cold temps, it can be several weeks, which can seem like it is dormant. Ich can ride in on plants and ornaments that came from an infected tank -- which is a good reason to let all your nets and decorations dry out if there is any suspicion of ich and to quarantine new plants. And, finally, the biggest one is the people who don't medicate long enough to kill 100% of the population. You have to medicate at least 5 days after the last time any symptoms are shown, and I usually recommend like 10 or 11 days, just to make sure that you get rid of 100% of the population. Because, again, if even 1 survives, it may grown back, and that can take months before the fish show symptoms again, and then the ich appears to come from nowhere -- like it came out of a dormant phase.

So, again, it is a preponderance of evidence that ich does not have a dormant stage. You can't prove a negative, there is a possibility a strain with a dormant stage hasn't been studied yet, but so far all the evidence is pointing one way -- that there isn't a dormant stage.

 

[annka5]

I can see that given the lifecycle is temperature dependent at very low temperatures then the parasite COULD be "ticking over" at such a slow rate that it is apparantly dormant.
However, I'm not sure that this would be "true" dormancy; also it would be an unobserved theoretical possibility (at the moment)- there isn't any evidence that it actually happens. Also, irrelevant for most (all, dependant on how low this temp is) fishkeepers.

 

[Jabba]

I'm not sure I agree that any number of Ich is irrelevant to any fishkeeper, on what is this conclusion based?.

So if we are to believe that even a small population can tick over but somehow remain small, then to my mind that is a very good indication that effective UVC sterilisation is a must even for freshwater tanks given the closed loop / artificial bio environments we create, eradication of parasites and other 'biohazards' that only degrade the species and environment they infest cannot be a bad thing.

I am leaning towards the 'failed to get rid of the Ich adequately' theory where I hear of constant recurrences, this then begs the quesiton though regarding the statements that a fish once it has been infested and 'cured' becomes immune or a carrier.

Consider this study >> Immune fish antibodies kill Theronts

Which if true, and to my mind this is a pretty thorough clinical study, means that not even a small population can remain and if it re-occurs then it must be re-introduced but then how, if a fish is now immune does it re-appear.

 

[Bignose]

Immunity isn't absolute, Jabba. Just like you can carry a cold virus and not have it make you sick, a fish can have ich (really small spots or in its gills) and not necessarily need to scratch, flick, or be otherwise inconvenienced. But, you can pass that cold virus onto someone else, and that fish can pass ich onto another fish. Also, immunity is usually only to one very specific strain. There are multiple strains out there, and again, continuing the cold example, if you got a virus that was very similar to one that you had already fought off, your body will be able to fight it off pretty quick, again you may not feel it, or only get a little sniffle instead of a full cold or flu. Same thing with ich, if the fish get a different strain, it may still infect an "immune" fish, but maybe not as much or as seriously. Immunity doesn't mean absolute 100% protection.

edit: look even at the first sentence of that link you posted, Jabba. The word the authors used was "reduced" not "eliminated" or "zero" or "none". Implying that some fish still got some amount of ich, though again probably not as much as they would have had without the immunization treatment otherwise.

 

[Jabba]

Firstly I am not convinced by the virus analogy since providing nothing is added to the tank then there can be no new strain introduced, and if there was something 'new' introduced then nothing would be immune other than the item introduced (perhaps) since any residents would not have been exposed to it. The only way a new strain - or any strain for that matter based on the evidence - can get in there is if WE put it there on a fish or plant, even then based on the article on treatment from the first post in this topic if you medicate properly for long enough then no Ich can survive.

Secondly I don't think it acceptable to take the first sentence in isolation and use that as a basis for a hypothesis, the study later explains that the Theronts that came into contact with the anitbodies showed high mortality rates, not only that but they were 'immobilized' and I take that to mean no chance to grow and feed properly and thus they would fail to develop into the Trophonts we see as the spots, also based on the statement

The immobilized theronts exhibited high mortality after exposure to either high concentrations of antibody or prolong exposure to low concentrations of antibody

In such a case then using simple mathematics the population that exists if significantly reduced at each generation, or indeed if unable to produce a generation at all must surely become extinct in the closed environment.

 

[Bignose]

These small, rapidly reproducing creatures do usually have a pretty significant mutation rate, too, Jabba. But, nonetheless, there is nothing in the article abstract (I don't have access to the entire text) that indicates that immunity is 100%. They talk about the percentage of apoptotic theronts increasing with the amount of antibody, not how every theront was destroyed in the presence of any antibody. If the population of ich is larger than the fish's antibody response abilities, then the fish will still get ich, even if it is "immune." Ultimately, each fish is an individual, as well. I am sure that you know someone who seems to get every single cold that goes through school or work, and conversely I am sure you know someone who seems to never get sick. Fish are the same way -- there are going to be some fish that won't get infected at any level, and some fish that will be infected by everything.

Without reading the article text, it is hard to know for certain what the authors were talking about. However, my interpretation of the word "immobilized" as the authors used it is that the theronts were immobilized on a slide so that they didn't move and the authors could check back on the same ones to see if they lived or died. Immobilized has nothing to do with how the antibodies work, in this case.

Next, without knowing what is meant exactly by "high mortality", it is also foolish to extrapolate to "simple mathematics" because the it depends on how high the death rate really is. Is the death rate greater, less than, or equal to the birth rate? Without that knowledge, mathematics are pretty much useless. Also, when dealing with microbial life, simple mathematics becomes ineffective at small concentrations. Eventually, the math will predict that there will be, on average, one half a lifeform left -- what does that mean? You have to start using the mathematics of stochastic processes to really get an understanding of what is going on. But, that is beyond the scope of this thread.

Finally, I actually want to address a point you made earlier about the use of UV sterilizers. A UV sterilizer can be good at decimating a population, such as ich. However, it can never get rid of 100% of a population on its own. That's because it never treats the entire tank at once, and the small volume of water it does treat gets mixed back in with the tank water. There is always a small percentage that a few lifeforms will exist because they aren't treated. That's why medications are necessary, because they treat the entire tank volume at once. In other words, there is no place to hide when using medications. Now, a UV sterilizer can keep the population of ich very, very low. Probably at the level that the fish will show no symptoms at all. But, if you ever take the sterilizer off, then that ich could grow back to problem levels.

 

[Jabba]

To a point I agree but the immobilization is chemical and is explained better in this article >> Surface Immobilization

I still find it hard to understand how any Ich at all can perpetuate in any tank in sufficient numbers to sustain a viable population if

a - You medicate properly and for sufficient duration on detection.
b - You do not introduce any other fish or organic material that could be contaminated.
c - The Ich is attacked by the fish's own immune system and after infection all fish become 'immune'.

if on top of this you run an effective UV-C system then I would expect (although cannot prove yet) that all traces of Ich can be wiped out in an aquarium.

Meaning that the claim that stress can induce an Ich outbreak, this too is a claim unsubstantiated by any science, and the claims of Dormancy are pure speculation and not proven, indeed the evidence available substantially says both claims are false.

I am afraid though that I find the 'mutation' theory in such a closed environment as an aquarium to be a little more of a highly unlikely remote possibility - given the number of generations needed for this, added to the fact that those generations must survive the encounter with the drugs or fish immune system in order to develop their own 'immunity' - if it took only one generation then we would be in a real mess as most of the diseases we face would be immune to the treatment once it had been used, I don't think I need any scientific back up to prove this case. Some strains of Malaria became immune to treatements largely because those taking the treatments did not complete the courses and allowed Malaria to survive that had been exposed to the drugs allowing them to develop their own immune system.

Unfortunately I cannot post more from the article(s), although all are available for a fee from the Journal of Fish Disease publisher (along with a lot of other interesting studies of Ich incidentally).

 

[Bignose]

Jabba, that is what I said in the first place. That if you medicate long enough and completely wipe out 100% of the population then ich cannot come back unless reintroduced from an infected fish or plant or net.

However, again, you are wrong in that a UV sterilizer alone cannot completely wipe out a population of ich. Again, it only treats a small volume of tank water at any one time and that treated water is remixed with the tank water. The UV cannot treat 100% of the tank at one time, so there is always some population left over that does not go through the sterilizer. It is probably going to be a very small number, but it won't be zero.

A population will stabilize at a point when the death rate equals the birth rate. Both the birth and death rates are functions of concentration of the population. There is a point -- because the functions aren't the same (birth rate is a power law, the death rate is probably linear) -- that they will equalize at an above zero population. So, there will always be some small amount of population left if you only use a UV sterilizer.

 

[Jabba]

I did not state UV-C only ....

I stated UV-C in addition to the other affects, particularly the medicate long enough and most people don't because the instructions with the meds they use are flawed.

 

[Bignose]

If you medicate long enough, then there isn't any need for UV at all then, because then the UV isn't actually killing anything. You actually can't do both at the same time, anyway, since UV will render most medications useless.