Lets Talk Ich For A Bit

[TwoTankAmin]

Most of us have probably had a brush or two with ich in our tanks. I am sure many have read all sorts of things about ich, However, I am willing to bet that relatively few people are aware of the fact that fish which have had ich and survived an develop an immunity to it, aka acquired immunity.
 

Abstract
Freshwater fish are able to mount a protective immune response against the parasite Ichthyophthirius multifiliis (Ich) following a non-lethal exposure. Factors involved in immunity comprise cellular and humoral factors, but antibodies have been suggested to play a prominent role in protection. However, host antibodies have not yet been demonstrated to bind to the parasite in situ. By the use of immunohistochemical techniques, this study demonstrated that IgT and IgM bind to surface structures, including cilia, on the early feeding stage of the parasite in the gills of immune rainbow trout, Oncorhynchus mykiss, shortly (2 h) after invasion. No binding of IgT and no or only a weak binding of IgM was observed on the parasites in the gills of similarly exposed but naı¨ve rainbow trout. This study indicates that antibodies play an important part in the protection of immune fish against Ich although additional humoral and cellular factors may contribute to this reaction.

from http/www.researchgate.net/publication/51642666_Experimental_evidence_for_direct_in_situ_binding_of_IgM_and_IgT_to_early_trophonts_of_Ichthyophthirius_multifiliis_(Fouquet)_in_the_gills_of_rainbow_trout_Oncorhynchus_mykiss_(Walbaum)/file/e0b495281cf2fb87f1.pdf
 
The above study is one is a number that have stated the aquired immunity factors relating to ich, here are a few more
 
Veterinary Immunology and Immunopathology
Review paper
Fish immunity and parasite infections: from innate immunity to
immunoprophylactic prospects
Pilar Alvarez-Pellitero *
http/www.idpublications.com/journals/PDFs/VII/VII_MostDown_1.pdf
 

Acquired protective immunity against ichthyophthiriosis is well recognised in teleosts (Buchmann et al., 2001b; Matthews, 2005).

 
 
Surface Immobilization Antigen of the Parasitic Ciliate Ichthyophthirius multifiliis Elicits Protective Immunity in Channel Catfish (Ictalurus punctatus)

1. Xuting Wang and
2. Harry W. Dickerson*

+ Author Affiliations

1. 
   
   Department of Medical Microbiology and Parasitology, College of Veterinary Medicine, The University of Georgia, Athens, Georgia 30602-7371
   

 

ABSTRACT
Channel catfish (Ictalurus punctatus) that survive infection with the parasitic ciliate Ichthyophthirius multifiliis acquire immunity to subsequent challenge and produce specific antibodies in serum that immobilize the parasite in vitro. Cellular surface protein antigens targeted by these antibodies are referred to as immobilization antigens (i-antigens).

 
I am wondering if folks here have any evidence of the above. For my part I have only had ich twice, in different tanks, in 14 years in the hobby and having 15-20 tanks going for most of that time. One sign that the above is the case would be having a tank with ich but having a number of fish in the tank not contracting it even though it is present.
 
 

 

[Chad]

...I am willing to bet that relatively few people are aware of the fact that fish which have had ich and survived an develop an immunity to it, aka acquired immunity.

I am aware of that and it's a very important part of how I deal with ich. I can't say I recommend my method to people but it's worked for me very well. 
 
It amounts to husbandry really. I make sure the fish eats, the water is clean, and that they do not become stressed then I let them deal with it themselves. Though marine ich is not the same as FW ich the treatment is the same for me with both Cryptocaryon irritans and Ichthyophthirius multifiliis,

 

[star4]

I have had a couple of instances:
 
1. I purchased 3 gourami from a LFS, the water was tinted - I was advised the fish had been treated for ich but were fine. Having purchased some other fish from the same shop I added them all to the QT tank, the other fish got ich but not the gourami.
 
2.  I had an elderly platy last year in a tank with other platies and other fish. One evening I noticed he was swimming with an odd action, swimming then resting, swimming then resting. He has lost condition over that week. The following morning that platy, and only that platy was covered in ich. I removed him and treated him and although the ich cleared he died a few days later. I believe the ich being present in the tank did not affect the healthy fish only the ailing older fish.
 
Yes it is possible for ich to only affect a single fish in a tank. I have quarantined fish that have never shown any problems including ich before being added to the main tank. I have only had to deal with an ich outbreak (more than one fish) in one of my main tanks once (pre quarantine)

 

[Chad]

Yes it is possible for ich to only affect a single fish in a tank. I have quarantined fish that have never shown any problems including ich before being added to the main tank. I have only had to deal with an ich outbreak (more than one fish) in one of my main tanks once (pre quarantine)

That is similar to my experience as well.