For myself, Atoll and Subsea, these silly diseases are a non-issue. I find it interesting that so many people allow their fish to get sick, as it is so easy to keep them healthy. Fish in the sea and in properly run tanks know how to stay healthy on their own without any input from us, as long as we feed them correctly, (with living gut bacteria) provide proper hiding places, and minimize stress, which is probably the most important factor.
(Premium dry foods are not the proper food)
To me, quarantine is extremely stressful and almost forces fish to contract something unless you can quarantine in something that resembles a fully set-up and mature reef tank, so the fish "think" they are in the sea. We never think of stress enough in this hobby unless it relates to us.
If your fish are constantly spawning, you know you have very healthy fish as all healthy fish spawn constantly. Or at least fill with eggs.
(That is fish that will spawn in a tank, not all fish)
Healthy fish also only die of a few things; old age is the most common cause, but some may be bullied or jump out. They should never die of a communicable disease, like never or we failed.
I personally would not put a quarantined or medicated fish in my tank, as it is not (IMO) a complete fish and will most likely have a shortened lifespan. I linked numerous scientific articles on that, so I have no need to do it again.
I realize many public aquariums quarantine. That doesn't mean it is correct; it just means they have not discovered the secret to keeping fish healthy naturally.
Fish live naturally in the sea while swimming in a sea of parasites and bacteria. They eat parasites and bacteria with every meal, which is how they were designed to eat.
I have not lost even one fish to any parasite in probably 45 years and I add fish from everywhere including the sea. How can I do that? And if I can do that, why can't most people?
Virtually everyone who says they used what you call "ich management" did it wrong. They either fed dry foods, medicated, quarantined, observed, dipped or tried to kill parasites one way or another and I have said numerous times, that won't work. If you want to do that method, you need to do the complete method, just like if you want to quarantine, you must do it correctly.
Why do you think when we see fish in quarantine, the fish get something else? I know why. Atoll and Subsea also know, and we know how to prevent that from happening to us. In over 100 years of combined fish keeping.
Of course quarantine works, but it is a temporary solution and not natural. Natural is how fish in the sea live, and in my 50 years of SCUBA diving, I have never seen a fish with any of the diseases I see in this hobby.
