Treating Mandarin with formalin?

[Seths Dad]

I wouldn't consider metro to be effective at eliminating all protozoa. It is certainly effective against luminal (internal) protozoa. Efficacy against ectoparasites (Brooklynella, Cryptocaryon etc.) appears to be hit or miss. Likely there is something about the pharmacological action of metro that is not effective against Cryptocaryon.

Personally, I would not use metro for Brooklynella. Formalin is a much more effective treatment.

I was treating based on this, am I misunderstanding something:
Prescription Medicines
Flagyl (metronidazole) is by far the most effective drug available against these diseases. Indeed it is the only effective treatment for fish that are internally infected with Uronema marinum, but it has to be administered in the diet. To treat with Flagyl (metronidazole), add 34mg/l (34mg/kg bodyweight is required if treating the internal disease) of the drug to the aquarium water to be treated. A single dose should be effective, but it can be repeated daily, if required, as the drug is well tolerated by most fish. It is a very reef safe drug having little impact on invertebrates BUT it will kill off all protozoans and anaerobic bacteria in the treated tank, so, like all medications that are used in a reef tank, it will have some undesired effects on the ecological stability of the tank.

 

[Deinonych]

Personally, I think that section needs to be revised as it's not consistent with recommendations from "trusted sources" like Noga's Fish Disease: Diagnosis and Treatment. Noga recommends formalin baths for both Brooklynella and Uronema.

Merck also recommends formalin for these parasites: http://www.merckvetmanual.com/mvm/exotic_and_laboratory_animals/fish/parasitic_diseases_of_fish.html

 

[Seths Dad]

Hmmmm.....confused, but that's not unusual

 

[Seths Dad]

Well I'm not sure what worked and what didn't or if it was a combination but after treating with formalin and metro I was able save my clowns and Mandarin. The female clown is finally eating after about 6 weeks so I think they are good. I don't see any signs of Brook. 3 more weeks in the QT then back in the DT. The mandarin is going to be very happy, pod's are everywhere.

 

[ThRoewer]

Hmmm. It does not just pop up without an introduction vehicle. Must be corals, inverts, or something wet.

I'm pretty sure all these protozoan parasites can hang out on fish for quite some time the way Cryptocaryon does. As long as the infected fish is in good enough condition to keep it contained.
Immunity is a way underrated mechanism here: In the present of the parasite fish can maintain their immunity indefinitely.
But one stressor can weaken the fish's immune system and lead to a full scale outbreak.