The best way to look at it is this way. Every thing in your tank could have ich. The rock, sand, coral plugs, etc. Ich feeds off of the fish. It needs the fish in order to survive. If you remove the fish from the equation the lifecycle of ich will be broken. They go through several phases of their life cycle. The cyst stage is what you see on the fish. That is the little white spots that you see. This is when they are feeding on the fish. They then drop off the fish into the sand and reproduce. They can stay in the sand for upwards of four weeks. There have been reports of even longer.


-Ben-