How to Treat ICH (The Important Stuff)
1. Check your water quality!!!!!! 9 times out of 10, the fish can do fine with a few Ichthyophthirius in the water, but when they are stressed by anything, like questionable water quality, it makes it much easier for the little buggers to set up shop in your fish's skin.
2. Do a 50% water change, just to be safe.
3. Add 3 tsp of aquarium salt per gallon to your tank. This reduces the osmotic stress on the fish caused by the invading organisms, and may adversely affect the organism as well.
4. Pick up an ich medication of your choice at the local fish mart. Most of the ones that are sold are more or less effective. My personal favorite is a malachite green/formaldehyde combination sold under the brand name "Quick Cure". ("RidIch" has the same ingredients.) Note: Most people recommend halving the dose of Malachite-containing medications if you are treating small catfish, any scaleless catfish, or tetras.
5. Disregard the instructions on the bottle!!!!! Use the DOSE written on the bottle, but treat like this: Treat every 3 to 4 days for 4 treatments, changing 50% of the water before every treatment. Do NOT treat once or twice, like the directions will tell you! You need to treat over 12 to 16 days in order to get all the little guys when they are vulnerable. (See life cycle diagram for explanation)
(Excuse the digression here, but this is my chance to vent my frustration at the aquarium trade -- I think they purposefully give poor medicating information so that the consumer will treat only partially, and knock down the parasite burden only enough to temporarily cure the fish! Because not all the organisms are dead, they will bounce back in a few weeks or months, and the poor consumer has to run out and but more of the ich medication! What a scam!!)
Other things which may help:
6. Raise the temperature in the tank above 85 degrees for 5-7 days. The tomites do very poorly at these temperatures, and it also speeds up the life cycle so more organisms are vulnerable to killing at any time.
7. You can use a diatomaceous earth filter to decrease the number of infective tomites.
8. Move fish to a clean tank after 7 days. This reduces reinfection by tomites left behind after the initial treatments