Have been scouring through mountains of information on this disease since it appeared and I'm now starting to think differently.
I've had a look at images of "marine Ich" using google. None seem to be what the wrasse had however I understand that these photos are usually of extreme cases of it and so my wrasse probably still has it.
Given the life cycle of Marine Ich, I'm thinking this fish already had it prior to adding it since the disease became apparent the following day after adding it.
Fish can apparently build up an immunity to this disease but it does not necessarily mean that the fish does not carry it nor does it mean that it isn't infected. The fish just may not exhibit the obvious symptoms that we can see and for the most part can live with it with some form immunity which helps it through and helps it fight low level infestations. Immunity does not necessarily last forever either.
"[/I]Fish can develop immunity to Cryptocaryon irritans that can last for up to six months (Colorni, 1987 and Colorni & Burgess, 1997). It is this natural immunity that makes evaluating the effectiveness of various treatment options so difficult. How can someone ever be certain that what they dosed to their tank or fed to their fish is what caused the cure they observed? The answer is simple, they can't. Until there are controlled, scientific studies, preferably repeated a few times, we cannot be sure that any of the newer homeopathic or "reef-safe" treatments actually work.
This limited immunity is also the basis for some aquarists advocating that if a fish gets sick, to just maintain pristine water quality, feed a superb diet, and to allow the fish's own immune system to do the job. While it is possible that this could work, natural immunity is not totally foolproof. In the studies cited above, some of the fish were not completely protected by their own natural immunity. It is possible that immunity could protect the fish from massive infestation, but still allow small numbers of parasites to remain and reproduce undetected by the aquarist. This is where the 'Ich is always present' argument comes into play and why sometimes an aquarist has recurring difficulties with this pathogen. It is possible, in some cases, that the treatment was cut short or misapplied or for some other reason not totally effective, but that immunity helped to partially ward off the infection. In this situation, a low-level infestation, held in check by natural immunity but not totally eradicated, could continue to survive but be misdiagnosed, or missed all together, by the hobbyist. The parasites could progress through their lifecycle by predominately attacking the gill tissue, where they could go unseen. Or, the number of parasites could be so low and their appearance (and disappearance) be erratic enough that the aquarist does not pick up on the infection or attributes the occasional white spot to a speck of sand or air bubble because the fish are behaving normally otherwise. That is until some other minor mishap occurs or the immunity wears off and the balance shifts in favor of the infestation, resulting in a full-blown infestation once again.
I want to be clear on this point. I do not believe Cryptocaryon irritans is always present in our systems. With a strict quarantine protocol, it is possible keep an Ich-free aquarium. I just believe that there have been enough hobbyists who have misused a treatment or utilized an ineffective treatment option, such that they never really fully conquered their initial infestation. Their continuing problems over the course of many months, and the posting of those experiences, seem to be enough to promote this aquarium myth. Cryptocaryon irritans can be eradicated from an infected system with a proven treatment and can be kept out of the system if good quarantine practices are employed.[/i]
I have also read several articles which debate the fact that marine ich always lives within an aquarium and I have to say I agree. The life cycle has been studied in depth and has been proven that it cannot lie dormant. It must go through it's cycle and must find a host. If the tank has been left to run fallow for a period of at least 8 weeks, then there is no way that it can still be alive.
If I am to leave the fish be and continue to feed well and maintain water quality, there is a high likelihood that any new additions will be infected and I will be forever battling this disease forever more. The fish may build their immunity however will still be carrying it, the disease will still continue to go through it's cycle and reproduce and will infect newcomers.
I am now starting to sway toward establishing my QT and removing and treating the fish with either hypo or copper treatment. I want to be confident that I have eradicated this problem completely and this seems to be the only way.
