This is part of a great write up by
@Humblefish on whether to treat or just observe new fish in qt:
"Once your fish are in QT, you must decide whether to prophylactically treat or just observe. This is a much debated topic. Personally, I feel it all comes down to knowing what type of person you are and how much free time you have to watch your fish in QT. If you are the observant, attention to detail type and have lots of time to watch the fish, then just observing may work best for you. All but two diseases - ich and flukes - will usually show themselves with visible symptoms within 1 month of QT. Ich may or may not have visible symptoms (white “sprinkles” on the fish), and flukes rarely are seen unless the fish is afflicted by Neobenedenia or badly infected (with cloudy eyes). However, both will usually have behavioral symptoms such as
scratching, flashing, twitching and heavy breathing. Prophylactic treatment is a wise course for those with hectic schedules or not overly observant. It involves just treating for ich & flukes, whether or not the fish actually have them. Available treatment options for both diseases can be found here:
https://www.reef2reef.com/forums/fish-disease-treatment-diagnosis/189284-fish-diseases-101-a.html
A fish should be left in QT for
a minimum of one month. Longer is always better, but one month allows enough time for most diseases to show themselves; although remember
ich & flukes may only have subtle, but not visible, symptoms (as outlined above). Since I prophylactically treat, my fish spend between 4 and 6 weeks in QT dependent upon which “option” I choose. I have never seen a disease in my DT since adopting one of these two protocols:
Option A - Fish is floated in the bag for 20-30 minutes (to temp acclimate) and then released into QT with matching SG. I give the fish a few days to recuperate and try to get him eating. Once he’s eaten for two consecutive days, I begin
Prazipro treatment - dose once, wait 5-7 days, do a 20-25% water change and then repeat dosage. Five days later I do another 20-25% water change and run activated carbon for 24 hours. After removing the carbon, I begin either Chloroquine phosphate or copper treatment for 30 days. After that, the fish should be ready for the DT - so long as he’s eating, looks healthy and isn’t displaying symptoms of any disease.
Don’t freak if the fish stops eating when you first begin
any chemical treatment. Prazi only remains active for 72 hours anyway, but prolonged appetite suppression (3-4 days) from other medications should result in discontinuing treatment.
https://www.reef2reef.com/threads/qt-protocol-flowchart.312531/
OR
Option B - Fish is floated in the bag for 20-30 minutes (to temp acclimate) and then released into QT with matching SG. “Option B” is tank transfer method, as outlined here:
Tank Transfer Method
Prazipro is dosed at the onset of “Day 4” and “Day 10” transfers; transfers 2 & 4 respectively. After tank transfer is complete, the fish is observed for an additional 2 weeks to watch for symptoms of other diseases. If the fish is eating well, looks healthy and isn’t displaying symptoms of any disease… he gets to go into my DT.
I use “Option A” mostly for larger fish; “Option B” for smaller ones. “Option B” does get the fish in your DT 2 weeks sooner, but it’s also a lot more work. If the fish arrives in low SG, as the water evaporates, just top off the QT with saltwater (instead of freshwater) until it matches your DT. So long as SG & temperature match, you can just add the fish to your DT without doing any acclimation procedure."
The whole article is here:
https://www.reef2reef.com/threads/how-to-quarantine.189815/