Snails can't get Ich, but they can carry them. What the duck overlord asked is important.
Here's a crash course on Ich life cycles.
Stage 1: The Ich has burrowed beneath the slime coat of the fish, and is immune to meds at this time. A salt dip may be used to get the Ich off the fish. Remeber, the white spot is not Ich, that is the fish's body's reaction to the parasite burrowed in it's skin. Here, the parasite feeds on the host. Enough parasites on a fish will overwhelm it, and kill it.
Stage 2: The Ich detaches itself from the host, and attaches itself to any surface in preparation to go into stage 3. I believe the Ich is vulnerable when it detaches from the host. However, when it clings to a surface, it creates a protective coat and is no longer vulnerable to meds. This stage is invisible to the naked eye. When the Ich comes out into stage 3, it will have multiplied.
Stage 3: The Ich is in its free floating swimming stage. In this stage, it is also invisible to the naked eye. It will swim around in the water until it finds a host to attach to. This is when Ich is vulnerable to medications (salt and chemical meds). If the Ich parasite cannot find a host, it will die.
There is no dormat stage of an Ich parasite. Therefore, any claims that say Ich is always present in a tank, and is an opportunistic infector, is just a false rumor. Without hosts, the Ich will die. The life cycle of the parasite depends on the temperature of the water, ranging from weeks in a coldwater pond to a 3-4 days in a tropical tank. There have been experiments that have found high temperatures alone can kill Ich (90 degrees Farenheit and higher).
Knowing the life cycle of Ich, if the parasite hasn't found a place to attach itself for a few days, it will have died. If there was only the snail, then the parasites may well have died. If there was a snail with anything that the Ich can play host on, then the snail might still be carrying Ich in stage 2 attached to the snail shell.
