[newatthis]

Ok I have read and read til my eyes have crossed. The tried and true method appears to be a fallow tank. The theory is that no host, no ich. But then I have heard ich is in some tanks and the fish just fight it off. Hypothetically if the fish are fighting off the ich, how is it able to reproduce and stay in the tank?

[smidoid]

Some the Ich parasite's lifecycle is detached from the fish. You have to treat the parasite and kill all forms of it in a hospital tank and leave the display to run fallow so the remaining ones die of starvation. Doubtless Lee will be able to fill you in on the details and best curatives.

[leebca]

newatthis,

WELCOME! to Reefland and this new Forum!

There are many fishes that have a pretty good resistance to Marine Ich (Cryptocaryon irritans). Mother Nature has 'selected' them to be resistant, and for some fishes, for a good reason. But I won't go any further on this, here.

I have kept marine aquariums for fish only for more than 35 years. Using a quarantine system, I have not had Marine Ich in my display tanks for more than 34 years. This means, 0 loss of life due to this disease, in my display tanks.

For infected fishes, there are three primary treatments to choose from. For an infected living tank there is one cure. . .going fishless for 8 weeks. If the tank is not living or empty, there are other sterilizing techniques to get rid of this parasite.

Now let's take your 'in-between' scenario. Marine Ich is in the 'living' tank and the fish are left to fend for themselves. Some fishes will develop an immunity to the disease, other fishes will develop a resistance. This last group of fish can handle the disease if the numbers of infecting parasites are kept to a minimum. How can they be kept to a minimum? Three parts are needed to come together on the fish-side: The fishes must be in perfect health otherwise; the fishes must be fed the correct nutritious foods (I will post soon a sticky on that subject -- look for it this weekend); and lastly, the fishes need to be free of other stresses (tank mate issues, tank size, water quality, etc.). On the tank system-side, a properly operating and sized UV can help reduce the free swimming stage (Theronts) of this parasite.

This group of fish, by virtue of their low-stress environment and general health can usually survive a minor Marine Ich attack. By "minor" I specifically mean "low numbers." The Marine Ich still infects them and reproduces, but the fish lives through this event. The Marine Ich remains alive in the tank but in very low numbers.

If something upsets that balance, (drop in temp, water goes bad, stress increases, you missed feeding the fishes, change in pH, UV bulb gets old, or any little thing) and the Marine Ich can 'bloom.' In higher numbers, the parasites overcome the fishes that were resisting it.

I don't believe in letting fish fend for themselves. Others think it is too much trouble to deal with this parasite by eradicating it and curing their fishes. Still others put their hopes in miracle cures and 'reef safe' cures (that usually don't work). But I wonder what the fish is thinking? This pet is infected. It is sick. Some aquarists say, 'Too bad, hope you live through it.' I say, let's cure the fish by known, definitive methods. I don't treat animals in my care on a 'good luck' approach. If they are in my care, I care for them.

Thanks for posting.