Hi Terry,
It's nice to see you back.
Here is my experience with the parasite.
I had my quarantine tank at 1.014 for 2 weeks at 81.6F while deciding whether or not to treat any additional fish (didn't want to drop it any further in case I was going to add any additional fish). The Cryptocaryon had no problem continuing its life cycle until I dropped it to 1.010. The only change I would recommend is increasing the time for the treatment. I treated all the fish originally for 5 weeks at 1.009 to 1.010 with the infected tanks fishless at 81.5F to 82.5F for 7 weeks. After 5 days, most of the fish returned to my 200 gallon was reinfected. The fish in the other 3 tanks appeared to be parasite free (even up to today). I collected the cysts (from an almost fresh water bath SG:1.005) and sent one dead fish (on ice for skin scraping - lost only one) to have it examined to ID the parasite. It was confirmed by two vets (specialize in fish research) to be cryptocaryon. Both advised that they have seen / heard of the parasite surviving up to 3 months without fish and recommended leaving a tank fishless for at least 2 months with 3 being ideal. The other theory is that is could possibility survive / dormant on the fish (only problem with this is that most of the fish in the 200 gallon showed visible spots within a day of each other).
The other interesting thing is that fish can and do build up a resistance to the parasite. The parasite still resides in the 200 gallon but there is no visible of it. After the fish had their initial outbreak upon being returned, I removed the worse fish (Achilles Tang - was covered with hundreds of spots in two weeks and placed back into quarantine). The few remaining fish in quarantine (just finished treatment and water back to 1.025) were reinfected with visible spots in approx. 6 days (back to hyposalinity). In the 200-gallon tank, the amount of visible spots reduced until by 3 weeks there was no visible sign of the parasite at all. I placed 5 neon gobies into the tank approx. two weeks later and all of them were covered with spots with a couple of the other fish getting only a few spots by the time of the neon's second cycle with the parasite. This lasted for almost 3 weeks. It is now a few months later and there has been no visible sign of the parasite since (not a single visible spot). I would conclude that it is still there but in a low numbers.
I did originally try kick ich w/o any effect at all. I was going to try garlic but was advised not too by the vets and two curators of public aquariums as it is unproved and that most fish will build up a resistance to it if the infections level is low (The Achilles seems to be the exception. All other fish including a sailfin and yellow tang seem to have built up a resistance).
For the 200 gallon I decided to use Dr. Ron's suggestion to build up the sand bed and increase the amount of sand bed life and coral that can use the tomites as food and help keep the level reduced.
On the note of temperature swings:
One of my kid's tank has 2 three spot demsels that were covered with white spots while they were in main tank. After hyposalinity treatment and letting a 20 long go 7 weeks without fish, they have no visible spots for many months. This tank was place (didn't realize at the time) near a ceiling AC vent. When his fan was on, the tanks temp would drop. I measured changes from 70 to 81F occurring daily between the window and vent. It has been corrected, but either fish showed any signs of the parasite.
The fish in the 200-gallon have also been stressed out with their light being turned on and the fish being caught in the middle of the night to remove 20 ciroloid isopods that came in on a live rock. This required catching the sleeping fish and removing the isopod that was attached to the fish with forceps on a sheet of plastic. No spots became visible during this time period or after it.
Bob
PS: If I knew that I was going to go through this with a reef tank, I would of put a nice picture on that wall instead of a tank.
** I am not endorsing or putting down any treatments, just stating my experience with this parasite.
[This message has been edited by Robert Schnell (edited 08-06-2000).]