This is a great thread.
I have been in this hobby for many years. I worked at a LFS for over 6 years and I can definitely without a doubt tell you that every fish in the stores system will have been exposed to ich, and any number of other nasties. I have a science degree and I am a researcher by profession, but having said that I do believe actual experiences are how we learn the most. I read alot…LOL… I have read just about every thread there is on ich that I could find on RC just because I am always interested in gaining insight into all things salty.
I don’t QT fish even though I agree with most everything Jon has said. If I ran a fish only setup I might try to achieve an ich free system, but the amount of work that it would take to do this in a reef setup is not something I can do. Do to my work I am out of town quite frequently and there is no way I could maintain the number of qt tanks it would require. You would have to qt everything, rock, corls,inverts, snails, ect… I have always had good success with great water quality, great diet, and keeping stress to a minimum. Does this mean I never lose a fish? Nope. I just lost my purple tang. It was the first and only fish in the 95g. I put it into the display tank knowing that it was exposed to all kinds of parasites, but it had been in the LFS for 3 weeks, was eating, and showed no obvious signs of ill health. I have no idea what killed this fish. Thankfully this is not something that has happened to me very often. I think over the ten years that I have been keeping salt water I have lost 6 fish to various mishaps.
I have a very fat and healthy hippo in my 39g. He should not be there, and by all accounts must be stressed somewhat by the small tank even though he is only 2.5". I was offered the fish by someone getting out of the hobby and since I new I was going to be adding a larger tank soon decided to go for it. This fish had a few spots on and off for about 2 weeks and has been free since then. He is one of the healthiest hippo’s I have seen in a long time. I think letting a fish build a good immune system will benifit it in the long run since I know future additions of anything to the tank will likely be carrying parasites, bacteria, fungus, you name it.
I do believe in doing everything to stack the odds in favor of the fish over the parasite. I run a properly sized uv on my tanks. I know it won’t eliminate the parastites, but it can reduce the numbers. I also add garlic a few times a week to the fishes food as it certainly doesn’t hurt. Over the years this system has worked well for me, I have lost very few fish to ich, (only two that I can say for sure), and have had many more survive without any specific treatment other than good water and diet.
These are just my experiences and what works for me. I think everyone needs to do the research and then draw their own conclusions based on experience and good advice from knowledgable hobbiest. I think alot of newbies get into trouble when they add too many fish too fast to a tank that is not able to handle the bioload. If you have a fish that dies of ich, or at least you are fairly certain it did, it makes since to wait a few weeks before attempting to add another. Why tip the scales in favor of the parasites?
Sorry for the long ramblings. It is hard to disscuss this topic when writing as there is so much to say about it from so many different prospectives.