Marine Ich and the 11 month "worn out" theory

[Ichthys]

More has been written on MI than perhaps any other facet of marine fish-keeping and without a doubt one of the big contributors to my own education has been reading the materials of Lee Birch. His articles and threads on several reef keeping forums are probably quoted more than any other single individual in the hobby. Unfortunately it does not appear he is still active on RF but he has left behind much valuable information.

I would like to put forth a subject for discussion, one that was originally cited by Lee as item 14 and has pretty much been adopted by the hobby community as fact.

14. INTERESTING FIND: If no new MI is introduce into an infected aquarium, the MI already there continues to cycle through multiple generations until about 10 to 11 months when the MI has �worn itself out� and becomes less infective. A tank can be free of an MI infestation if it is never exposed to new MI parasites for over 11 months.

Herefishyfishy asked about this in a 2007 thread and many of my questions are the same as his, I am curious if there has been any evidence supporting or contrary to since this was first reported. The science this comment was garnered from took place in 1994, almost 20 years ago and one would think that in the interim some supporting or contrary scientific study might have been undertaken, yet I am unable to find anything concrete which cites actual scientific methodology.

Here is the quote from the original article which started this line of thinking which most of us all now just accept as fact.

Burgess and Matthews (1994) were attempting to maintain a viable population of C. irritans which could be used in later studies. To maintain the parasite populations, they needed host fish in order for the trophonts to feed and continue the life cycle. Each host fish was only used once in a process of serial transition such that none of the hosts would die or develop an immunity. While the procedure worked very well and enabled them to maintain populations for some time, the viability of the populations decreased with time and none of the 7 isolates they used survived more than 34 cycles, around 10 to 11 months. They suggest this is due to senescence and aging in cell lines is well recognised in Ciliophora.

I have read contrary opinions over time (unsupported) that there is no scientific basis that parasites do not "wear themselves out" and that the above finding has no factual basis.

I just wanted to open a friendly discussion of this topic and solicit any new science supporting or against #14. I would also like to say, I have the utmost respect for the body of literature contributed to the hobby by Lee.

Thanks
Ichthys

 

[trido]

I have read contrary opinions over time (unsupported) that there is no scientific basis that parasites do not "wear themselves out" and that the above finding has no factual basis.

I think that in most cases the Ich is still cycling well after a year but that the fish in our tanks are not stressed out and are pretty immune to the specific strain that is in the tank and we do not see the parasite. I do believe that it likely never goes away. In my last tank the hippo tang would show ich every time I would go on vacation even after several years. I wasn't adding fish to the system regularly and the ones I did add never showed Ich at all.

 

[NC2WA]

+1 to what Duane said about in water but fish are immuned to it, but any new fish added would prolly get it asap.

which leads to my question which may be another topic: what does one do for new fish in this situation? QT or not?

 

[Rea17]

I have a huge amount of respect for the information that Lee has presented here for us, and there may be some validity to the "worn out theory," but I don't think it has much of a practical application in our tanks. Many hobbyists adopt the method of thinking that if they can't see the ich - it isn't there. They then experience similar things as what trido stated, and ich becomes something that "is in all of our tanks." As Lee has said - myth. It should also be mentioned that in the article Ichthys quoted, new fish were cycled through the ich to prevent immunity or over infestation of the parasite. Once again, this is not a practical application for our tanks.

I know a few local people who cling to the "worn out" theory as an excuse to not quarantine or treat their fish, and I am not a fan. In the end it is the fish that suffer.

 

[Herefishyfishy]

I have some personal experience that the ich "inbreeding" leads to failed genetics theory and support it through anecdotal observation. One must keep in mind when trying to apply, for an entire year, from any other tanks, locations, etc, NOTHING WET CAN BE ADDED TO THE DISPLAY! No fish, no corals, no shared nets, hoses, pumps, no used equipment, and even some frozen foods might cause risk. Nothing wet besides water. For most of us, this is not possible due to temptation. Want to test if you have MI in your display? Add a young tang from the wild. You will know in under two weeks. . .

 

[Herefishyfishy]

One more comment on the use of the word immune: Fish do NOT develop an immunity to Ich. Some can avoid symptomatic infestation from them, but as C. irritans is not a bacteria nor virus, there is no immunological resistance possible. Even clownfish with a thick mucous membrane system are not immune. Similar to humans not being able to get an "immunity" to mosquitos, bed bugs, head lice, etc..

Some fish have very little defense to MI such as tangs. As an infected tank's C. irritans ages and cycles over and over, the combined resistance from infected fish and the weakened ability of MI to reproduce can make one feel all is good. The introduction of a young tang which has been QTed in copper (not a carrier) into the display, will show the poor fish soon badly infected.

 

[Rea17]

One more comment on the use of the word immune: Fish do NOT develop an immunity to Ich. Some can avoid symptomatic infestation from them, but as C. irritans is not a bacteria nor virus, there is no immunological resistance possible. Even clownfish with a thick mucous membrane system are not immune. Similar to humans not being able to get an "immunity" to mosquitos, bed bugs, head lice, etc..

Some fish have very little defense to MI such as tangs. As an infected tank's C. irritans ages and cycles over and over, the combined resistance from infected fish and the weakened ability of MI to reproduce can make one feel all is good. The introduction of a young tang which has been QTed in copper (not a carrier) into the display, will show the poor fish soon badly infected.

+1 Well said. I should have said symptomatic, not immune.

 

[kpiotrowski]

yes if you get bit by a mosquito in your home and then expect that you can step out into the wilderness where are swarms sometimes off literally tens and thousands it's really hard to believe that considering the amount of parasite is constantly increasing with each cycle that a fish can develop immunity against the parasite attaching to them. Just trying to make sense.but on the flip side I suppose it's possible that the fish to develop some sort of a chemical compound that would make it distasteful to the ich parasite?

 

[spieszak]

I've always wondered if the temporary immunity thing that some have seen has to due with scar tissue in the gills. No scientific basis to the theory, just a musing on my part. If the gills get scarred up from infestation, and rich loves the gills...

 

[Herefishyfishy]

I've always wondered if the temporary immunity thing that some have seen has to due with scar tissue in the gills. No scientific basis to the theory, just a musing on my part. If the gills get scarred up from infestation, and rich loves the gills...

If the gills scar up or become changed in any way, the fish dies. Need the miracle of gas exchange to occur unimpeded.

 

[spieszak]

If the gills scar up or become changed in any way, therich sh dies. Need the miracle of gas exchange to occur unimpeded.

Hmm... maybe you can explain the error in my logic trying to follow this. So, the ich Attaching to the gills changes the gills as water flow would be blocked at the attachment site right? Therefore 'changing the gills' ... so, any ich infected fish should die?
I'm not attempting to call you out or anything, I'm just trying to understand how what you've noted can be true at the same time a fish doesn't have to die from ich when properly treated...

 

[Herefishyfishy]

Hmm... maybe you can explain the error in my logic trying to follow this. So, the ich Attaching to the gills changes the gills as water flow would be blocked at the attachment site right? Therefore 'changing the gills' ... so, any ich infected fish should die?
I'm not attempting to call you out or anything, I'm just trying to understand how what you've noted can be true at the same time a fish doesn't have to die from ich when properly treated...

You are overthinking this. Untreated, a weak fish dies, a lucky strong fish lives. The parasite reproduction cycles until genetic mutations kills it off from lack of gene pool unless new Ich is introduced. A fish with gill destruction is not stronger, it is dying. The signs of this is rapid respiration development as tomonts, mucus, and tissue debris clogs the gills.

 

[spieszak]

well, no i'm not overthinking it, you've confused me.
gill damage bad. simple fact. doesn't change the supposition that the temporary immunity could be based on gill damage or scar tissue. ich is not a bacteria or virus, therefor immunity should not be able to be developed. i don't know why some fish see a temporary immunity, and the damanged gills making it harder to attach/reproduce was just a theory.
ich is preventable and highly treatable if you just make the effort, so, its kind of a useless venture to wonder about it anyway.

 

[Herefishyfishy]

Stacey, would getting emphysema help give you an immunity to pneumonia or lungworms?
Just saying that gill damage does not improve survival potential, especially against an invader.

 

[spieszak]

No, but your bodies natural defense against airborne contaminants is the mucous in your nose and throat. It basically allows you to digest the contaminants rather than allow them into you respiratory system. Evolution developed that system because it was the most efficient means it could manufacture to work at eliminating the containment. Ich is a parasite, its not something that immunity can be developed against. Its an external factor. The fish cannot develop an immunity in the true sense of the word, it would have to come from a "work around' such as the mucus noted earlier. So I'm not suggesting its a good thing, nor that it would be healthy for the fish, nor that anyone should live with it long enough to try to figure out where this immunity comes from. What I'm suggesting is that gill damage is a possible explanation as to the end around created allowing some fish to show an immunity short term. It could very well be simpler than that, and its just an increased slime coat, or something else. I was just 'supposing, wondering out loud (in print)'.
And as I noted earlier, its a useless "supposing", and I probably shouldn't have bothered to post it as it has apparently created a bit of controversy. Ich sucks, but we have known prevention and treatment methods that work. I posted it as a curiosity, not a fact... In most cases you don't get better by getting damaged or 'more sick', I agree. There are caveats to that though (such as flu vaccines that actually give you doses of a less viral/active/whatever strain of the flu), and I was just playing a 'what if' type game.

 

[Herefishyfishy]

No problem at all, have enjoyed the chat and much knowledge through the years has been gained by ponderings such as this. I like your increased slime coat theory. Cheers!

 

[Maxx]

+1 to what Duane said about in water but fish are immuned to it, but any new fish added would prolly get it asap.

which leads to my question which may be another topic: what does one do for new fish in this situation? QT or not?

I always QT'd new fish to my system which had ich previously and never went through a fallow/fishless period.

Never had any ich show up on new arrivals to the system, (Including a Powder Blue Tang hybrid) and would rarely see a spot or two on my Tomini Tang.

This is anecdotal and based on observation, and not scientifically documented, but its proven true in my system.

 

[kpiotrowski]

I've always wondered if the temporary immunity thing that some have seen has to due with scar tissue in the gills. No scientific basis to the theory, just a musing on my part. If the gills get scarred up from infestation, and rich loves the gills...

the ich parasite is everywhere on the fish...even the eyes. The gills are the most delicate tissue with best blood supply and hence easiest and most desirable place for parasiites to attach. You must understand that gas exchange in the the gills happen on a membrane that is a single cell thick. any scarr tissue is a non-working surface of the gills. the fish would simpley cease to exist under the theory you propose. and then you still have to tell us how the parasite is not attaching to the rest of the fish too. is it the same scar tissue theory?

I have already stated on this thread that I will lend some credence to a theory of it is possible to feed your fish a diet which may in turn make the fish undesirable to the ich paratiste ( garlic is a common one) and on that same note may explain how a fish may be able to develop its own immunity via unpleasant or toxic compounds. "also the 11 month ich wears out" studies were done a long time ago!!! be nice to see some more recent data.... and less magic potions!

 

[NC2WA]

I dont buy the garlic theory...Steven Pro did a study in which they found no scientific evidence to prove that garlic increases a fish immunity or for that matter kill a parasite..

 

[SkimHeavy]

I don't buy the garlic idea either. One thing I have seen is where people say, if you have ich in your tank and a fish breaks out he will not be able to kick it. It will continue to cycle over and over until it kills the fish. I have seen a member here who had an Achilles tang that would break out in ich all the time. No meds and no qt. I would drop off and be fine for weeks. He still has the fish 3 years later. Achilles are ich magnets. If he can shake it or live with it then lots of fish can.