I employ the following qauarantine protocol and results are quite promising, it also works for wrasses, pomacanthids etc.:
I use bare bottom glass aquariums just with an airstone in them. It is based on tank transfer method with some modifications to be even more effective.
1. At arrival, after drip acclimation and few hours of rest I give the new fish a formalin dip (1 ml of fresh formalin per 1 gal of water) for 30-45 min. But only if the fish are in good condition, with no open wounds.
2. First 3 days in first TTM tank with just normal seawater (fresh mix or from noninfected display system). If some doubts about ammonium accumulation, add few drops of ammonia remover. Do not overstock the quarantine.
3. another formalin dip with few drops (4-5 per gal) of malachite green in a bucket for 45 min. under heavy aeration (formalin causes oxygen depletion in the water).
4. transfer to tank 2 - again with just airstone and seawater, plus I add 1 pill of Entizol (250 mg of metronidazole) per 30 l (8 gal). In this case I add no other additives, because bad or unproven combination of chemicals may kill fish quickly
5. after 2-3 days (depending on water quality in quarantine tank) I give another formalin + malachite green dip
6. transfer to tank 3 with metronidazole
7. repeat this for a minimum of 5 transfers and the fish should be clean.
Few comments:
Formalin dips are just for fish in generally good condition, avoid them in case of open wounds or heavy stress. Othervise they are well tolerated.
Use new seawater for the dips, not water from quarantine or water with any other medication.
In case of new fish, I usually start to dose metronidazole after few days, when the fish are already eating. It is sufficient to keep fish in metronidazole continuously for ca 7 days. So it is not mandatory to dose it during the whole quarantine period.
Water with formalin should be pre-aerated for at least 10-15 min. prior you put the fish in.
Repeated formalin dips will kill external pathogens like flukes, bacteria, fungal agents, Brooklynella. They simply disinfect the surface of the fish.
TTM and metronidazole will break the cycle of the two main protozoan parasites (Amyloodinium and Cryptocaryon) in synergistic way.
Although it may sound complicated, the only difference from original TTM is the formalin dip (+ malachite green) between transfers and metronidazole added to water in the quarantine tank.
When you finish the TTM, you should place the fish in a disease free environment, otherwise the problems start again.
In case of arrival of wery sensitive fish with no visual symptoms, I keep it for first 2-4 weeks in a refugium-like quarantine tank for acclimation and to get it on food. After this period I run it through TTM just to be sure it is not a disease carrier.
Some fish like chaetodontids or pomacanthids often suffer from infestation by intestinal worms. To fix this, you may change metronidazole for praziquantel in the last transfer. But that is useful for new fish, not for the situation discussed in this thread.
I did this many times with fish like Pseudanthias, Oxymonacanthus, Paracheilinus, Pomacanthus, Chaetodon etc. with good results (means clean fish and minimal mortality). Obviously, if fish are initially in poor condition, you will have some losses whatever you do. Unfortunately, this is also my experience with some shipments from DeJong.
