Debaser said:
My blue hippo tang gets ich once a year for a week, then its gone. This has been going on for 3 years now. I think its because it's winter here in Wisconsin, so my tank runs cooler on weekends when I'm gone and I turn down the heat in the house. It just places stress on him. My maroon clown is totally unaffected and shows no signs of ich. Just because your fish loses those white spots doesnt mean that ich has vanished from you tank. I could very well sprinkle fairy dust in my tank and claim that it cures my ICH for up to a year.
No one should be allowed to post in this thread unless they have done their reading on ICH. LOL
Based on what is currently known about
Cryptocaryon, I believe it is very unlikely that what you are seeing is "Ich".
I doubt that
Cryptocaryon could survive in your tank for more than 12 months, let alone 3 years. Researchers have been trying to devise methods to propagate
Cryptocaryon in the laboratory to allow study. Burgess and Matthews (1994) serially used mullet to host the parasites. They would infect the fish and collect the tomonts after they left the host. The tomonts would be incubated and on excystment, a new set of fish would be infected. This method greatly favours the parasite and as each host fish is naive, it will successfully host the parasites.
Burgess and Matthews method worked extremely well, it was short lived. Of the 7 isolates they tested, 6 only survived for 7 cycles (around 10 weeks) and one survived for 34 cycles, which is shy of 12 months. For the short-lived 6 isolates, they found that the parasites lost viability and infectivity over time. This was not seen in the other isolate until around 30 cycles. The exact same phenomenon has been reported by researches of
Ichthyophthirius and it is believed that aging in the cell lines and the absence of genetic exchange (sexual reproduction) is the cause.
If under ideal conditions for the parasite, survival beyond 12 months is unlikely, I believe survival of the parasite is even less likely with non-naive fish.
Now, to your observations.
You believe there is
Cryptocaryon in the tank and once a year your tang gets stressed, becomes infected for a week and then recovers. Forgetting about senescence for the moment, for what you suggest to occur, the tang would have to have a partial immunity to
Cryptocaryon. This would enable the fish to host a small number of parasites without showing any signs of infection and it would also allow the parasites to keep a small population going. You believe the stress of the lower temperature on some weekends (I assume it is more than one) causes the fish to lose the partial immunity and the fish can then become fully infected. However, the fish only gets infected the one time and then regains its (partial) immunity. i.e. the stress was enough to cause it to lose its immunity but not enough for it to regain it.
For this to work, the stress from the cold (assuming it was enough to change the fish's immunity) would have to coincide with the theront stage in the life cycle of the parasite, which will be one day every 10 (on average). Given the water is colder (which would disadvantage the parasite), the life cycle may be longer, and so it would be one day in say 14 or more. If the colder conditions happen infrequently, the chances of the two events coinciding would be greatly decreased. If the colder conditions occur quite frequently, the coincidence would be more likely, but also the stress would be more prolonged, decreasing the chances of the fish reacquiring immunity.
Then there is the clownfish which never gets infected. This suggests it has full immunity to
Cryptocaryon. The only research we have to date on full immunity (Burgess and Matthews, 1995), demonstrated that full immunity only lasts up to 6 months (at least in mullet). I have to wonder how the clownfish is staying protected for all this time.
Of course, none of this proves anything. It is still possible that your tang does have a partial immunity to
Cryptocaryon and once a year that infection gets bad enough to be visible and then the fish recovers, however, in light of what is known about the parasite, it seems unlikely. Without positively identifying the spots as being caused by
Cryptocaryon it is all speculation.
Just to give you a quick start I'd suggest setting up a hospital tank and moving the tang in there. When you post to the disease forum, give as much information as you can on the fishes appearance, tank water parameters and even pictures of the fish if you can.
