Want some clarification on ich

[horseplay]

Can an ich-resistant fish carry ich for a long time (keeping the lifecycle of ich going while not being affected by it)? If so then will a new ich-free fish be infected by the ich-resistant fish carrying ich?

 

[snorvich]

The small number of fish that are ich immune can still carry ich and they can in fact pass it on to other fish that are not ich immune. (this is true of other parasites as well). Immunity typically last for six months.

 

[horseplay]

Steve - thanks for chiming in.

I suspect a lot of fish are immune to ich (or less likely to host ich). For example, I have a Kole Tang that initially had ich (or so I though) which went away in a few days without treatment. I have other before and after the Kole Tang was added and none ever had ich. So either the Tang is no longer carrying ich or the rest the fish are immune to ich.

What does " Immunity typically last for six months. " mean? Does it mean if the tank is ich free for six months and there is no fish addition the tank is completed ich free?

The reason I ask these question is that my tank had ich before (minor as mentioned) and I want to come clean and QT in the future by I need to start from a clean slate. There is no reason to QT (for purpose of ich) if the tank has ich anyway.

 

[snorvich]

Immunity going away means that the fish will be susceptible to ich. What I do not know is if immunity for one strain of ich (there are many strains) means it is immune to all strains. I strongly advocate quarantine for all fish since ich is the least problematic parasite.

 

[gone fishin]

Typo Steve?

 

[snorvich]

Typo Steve?

Fingers and brain were not synchronized. Thanks!!! :love2:

 

[gone fishin]

I have seen an unusual amount of posts the last few months about immunity and ich. Is there some new research out about this or just wishful thinking.

 

[ThRoewer]

The small number of fish that are ich immune can still carry ich and they can in fact pass it on to other fish that are not ich immune. (this is true of other parasites as well). Immunity typically last for six months.

Do you mean fully immune or rather partially immune?
While full immunity may be rare, I feel partial immunity is pretty common. I see it at the local stores all the time where some fish are dying of ich, velvet or brook while others of the same genus seemed to be completely unaffected. Those are usually the ones that have been there for a while and previously survived an infection.
I feel fish who always live in the same space/cave are more likely to develop (partial) immunity than fish that roam the reef or the open sea.
It makes sense that a fish that will stay where the parasites dropped off and multiply needs to find a way to survive the next wave while a free roaming fish doesn't need to bother as he will be far away by the time the next waves hatches.

The majority of the Cryptocaryon research has been and is still done on food fish which fall usually into the second category (open ocean fish). So the findings on immunity are likely skewed towards these.

As for the six month - that limitation is only if no parasites are present.

 

[snorvich]

The majority of the Cryptocaryon research has been and is still done on food fish which fall usually into the second category (open ocean fish). So the findings on immunity are likely skewed towards these.

I agree

As for the six month - that limitation is only if no parasites are present.

I disagree. Fish with temporary immunity are known to be carriers. Fish that survive a Cryptocaryon infection develop immunity to that particular strain of Cryptocaryon, which can prevent significant disease re-occurrence for up to 6 months (Burgess 1992; Burgess and Matthews 1995). However, these survivors act as carriers and provide a reservoir for future outbreaks (Colorni and Burgess 1997). What has not been tested is whether those with immunity are immune in a strain specific manner only.