1000 posts!
Honestly there is no such thing as an EXPERT in ich. There just isn't enough known about this parasite to sound all high and mighty one way or the other.
Raj - marine ich and freshwater ich are two separate parasites. Freshwater ich can quickly become fatal, marine ich... not so much
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The following is my opinion on ich:
The goal of any good parasite is to live in equilibrium with its hosts. Marine ich is a very good parasite in that virtually every home aquarium has ich. Yet most home aquariums with ich do not suffer fatalities. In fact I only know of a few home aquariums that have had catastrophic losses from marine ich. Brandon is unforunately one of those people, and so I understand why he is such a proponent of eliminating the parasite in entirety from the tank.
However, most other people, myself included, have ich in their tanks and have had it for a number of years with no losses. Its basically a non-issue for most of the reefers out there.
Why then does it cause catastrophic losses in some tanks and not others? Honestly, we don't know that because we know so little about the parasite. Yah we know how to stop it, yah we know what it does to the fish, but we don't even know what mechanism it uses to locate hosts. I'm a believer that the ich tomites require a dirty environment with some sort of nutrient supply for ich to really take off. In the three tanks of people I actually know who had marine ich fatalities, all 3 kept their tanks pretty dirty intentionally or from neglect. That's hardly conclusive evidence, but I notice that I get a few spots on my fish here and there if I become negligent with my housekeeping.
Conclusion:
Do your best to keep ich out of your system with QT if you can. However, undoubtedly even with best efforts... you may get ich in your system. If that occurs, do not panic, do not immediately QT your fish and begin treating your system for ich. That's is just foolish and could lead to other stress related deaths like this poor flame angel! Wait a lil and see what happens... more than likely if your fish are healthy to begin with they will fight it off and live in equilibrium with the parasite, like in most of our tanks...