So, I've been doing some research and to answer a couple of my own questions:
- I have found no information suggesting that ich trophonts can remain on a fish for longer than 7 days. Everything I've read just regurgitates the "3โ7 day" window found in the stickies; even though most of the info does discuss discrepancies when it comes to things such as tomont/trophont size, the time it takes for theronts to be released, etc.
- Velvet has a very fast total life cycle, typically 3 to 6 days. Which explains why it is so deadly and such a fast killer - the fish are just overwhelmed. Also, chemical treatments such as CP are only effective against the dinospore stage (same as the theront stage in marine ich).
Extrapolating what I've learned, my theory is that a newly acquired fish infected with trophonts of either disease can be cleared of both in as little as 10 days
IF:
1. The fish is treated with Chloroquine phosphate in a bare bottom QT (no rock/sand or anything else which might absorb the medication). CP (at a dosage of 40mg/gal) should already be present in the water before the fish is added. Copper is not suitable for this experiment, as it needs to be raised gradually.
2. After 10 full days of exposure to CP, the fish should then be moved to another QT (same as doing tank transfer - all new water/sterile equipment). This is how the fish "escapes" or leaves behind whatever life cycle of the parasites that remain in the original QT. You also must be mindful of aerosol transmission, so space the two QTs accordingly. The time spent in the second QT can be used to treat with Prazipro and/or observe for other diseases.
I believe this method will work because the presence of CP should "shield" a fish from reinfection, since it targets the theront/dinospore stage. And 10 days should allow more than enough time for all of the trophonts to drop off an infected specimen. Please keep in mind I'm not advocating this as "proven", or suggesting anyone trust this method at this time. But for those of you, who like me, enjoy experimenting with "outside the box" thinking... I'd appreciate hearing about your results. I personally plan to try this out on my next fish. If this QT method ends up failing me at some point, I have no problem saying, "I was wrong". I have no ego to bruise (like Mr. Spock

).