How Long Until "in the clear" for Ich?

[texhorns98]

OK,

So I didn't QT any of my fish I've been adding for the past few months (I know, I know). Does there come a point in time when you are "in the clear" for Ich? Or is Ich something that can spring up later?

[returnofsid]

If your fish are carrying Ich, any stress can cause it to "spring up." The myth that Ich is in all tanks is just that, a myth. You can rid your tank of Ich with hyposalinity, if you don't have corals. If you have corals, all fish would need to be QTd in hyposalinity for 8 weeks and display would need to remain fish free, with NO fish, for the same 8 week period. After that, you're Ich free. Then just making sure you QT everything that goes into your tank will keep it Ich free.

[tmz]

After a month without any signs, I would be pretty confident. However, the parasite often hosts in the gills, nostrils and mouth unseen ,so you never really know.

[FOSELONE]

it could also come in on a new fish & infect your others...

[kevin2000]

No right answer.

Ich is one of those parasites where you have to kill every single one to have an ich free tank. Its very common for ich to survive at a nominal level within a tank for a prolonged period of time - then suddenly resurrect itself during a stress event or when the fish lose whatever immunity they may have build up for that parasite.

[tewkes]

Just to add to what the others have said.

From what I heard (or read) that most fish carry ich but it doesn't present itself unless stressed by whatever reason.

I think there are definetly fish (hippo tang) that are more susceptable to having it brought out.

[crvz]

Some folks don't believe there exists an "ich-free" tank, as the parasites can lay dormant for months. If something in the tank goes south, and the fish are stressed or otherwise suffering, you may see it spring up, but if it's been 2-3 months already I wouldnt be terribly concerned.

[tmz]

Marine ich(crytocaryon irritans) seems to be everywhere but it's not. It is rare in the wild and most marine fish caught for the hobby don't have it when captured. It seems to be a product of the congregate confinement which occurs in the chain of custody from the ocean to your tank and then the confinement of your tank..Even then many if not most of the fish you acquire are ich free.

In my opinion, ich can be prevented from occurring in your tank by following robust quarantine protocols from the very beginning . Wether or not to include prophylactic treatment in quarantine is a debatable subject with some preferring not to use medications on a fish that may not need it.This protozoan can,however, hide in the mouth nose and gills of a fish and remain undetected until it breaks out.
It also must leave the fish after a week or two to sink to the bottom or other surfaces and encyst and multiply(200to 300 fold). Within another week or so it will swim out and look for a host. The cysts have been able to survive for up to 72 days in cold water but under normal aquarium conditions generally all will perish without a fish to host it with in 6 weeks.

The only way it will get into your tank in the first place is on/in a fish or perhaps in encysted form on a piece of rock or gravel that has been exposed to an infestation within a few weeks of entering your tank.

Once the parasite is in the tank, it will be there for a long time if not indefinitely. There is one study(Burgess and Matthews 1994
) that suggests a single strain will perish after 34 life cycles due to cell aging, but it's only one study and one strain. Perhaps it offers some hope for those situations where removing all fish is just not a viable option.. There are thousands of strains of ich with variable virulence.A tank infested with ich needs to be left fishless for at least 6 weeks to errradicate the ich in the tank.

Infested fish need to be treated with copper( curpamine is a good product ) ,hyposalinity or the tank transfer method. While some fish can survive an ich infestation and even develop partial immunity, they will likely still carry some parasites even if unseen .And that's only if you are lucky enough to be hit with a less virulent strain.Treating quickly in a quarantine /hospital tank is important since the second infestation is almost always much worse than the first one.

Again quarantine is an essential part of husbandry in the keeping of marine fish. An Ich free tank is in my opinion an achievable and worthy goal but not an easy one.

[kevin2000]

Originally posted by tmz
Marine ich(crytocaryon irritans) seems to be everywhere but it's not. It is rare in the wild and most marine fish caught for the hobby don't have it when captured.

I seem to recall a study that indicated that about 1/3 of the wild fish collected during the study had ich - that was much higher than my expectation - might be unique the the area they did the study. Of course fish/ich in the ocean don't suffer the confinement of a tank and I doubt they get more than a few trophonts which would not cause harm.

[tmz]

Originally posted by kevin2000
I seem to recall a study that indicated that about 1/3 of the wild fish collected during the study had ich - that was much higher than my expectation - might be unique the the area they did the study. Of course fish/ich in the ocean don't suffer the confinement of a tank and I doubt they get more than a few trophonts which would not cause harm.

I'd be interested in reading that sudy if you have a cite you could share? I always thought it was much less than a !/3.In any case it's a bit esoteric since we all know we get plenty of ich on the fish we get.
I agree that confinement is probably the cause for the higher incidence of ich in aquariums. The vastness of the sea and perhaps predation on the parasite, it seems, would make a reinfestation much less likely than in the confines of an aquarium with recirculating water than in the ocean where many of the parasites would be washed away or eaten.