Ick, sometimes known as Ich, or white spot disease is one of the most common disease in home aquarium.  It is also one of the most easily cured if caught in time and treated properly.

Ich is actually a protozoa, Ichthyophthirius multifiliis, which is a memeber of a large group of single-celled, usually microscopic, eukaryotic organisms, such as amoebas, ciliates, flagellates, and sporozoans.

An acute Ich infection will look like white grains of salt imbedded on the exterior of the fish, and sometimes the fish will scratch against rocks and decorations in the tank.

There are three phases to the life cycle of this protozoa:
1. Adult:  It is embedded in the skin and/or gills of the fish and can be seen as small white spots on the surface of the fish.  As the parasite grows it feeds on the red blood cells and skin cells of the fish.  After a few days it bores out of the fish and falls to the bottom of the aquarium.

2. Cyst: After falling to the bottom the adult forms a cyst which is invulnerable to treatement.  During this stage it divides into 200 - 800 larvae (or tomites).

3. Free Swimming:  The tomites then swim around the tank looking for a host fish, into which they burrow and then grow into an adult continuing the cycle.  If they do not find a host they usually die within 2 - 3 days.  It is during the free swimming phase that they are most vulnerable.

At a temperature of approximately 70F this three phase process takes about 4 weeks.  However, increasing the temperature to 80F greatly speeds up the cycle and thus the opportunity to kill the parasites.  If the fish can stand it (and it depends on the species) temperatures as high as 85F are recommended.

With that background information here are my recommendations:

1. Add Doc Wellfish's Aquarium Salt:  Add approximately 1 tsp of this salt (not table salt!) per gallon.  Doissolve it in the aquarium water, in a separate container and only add salt to about 15% percent of the water per day.  Basically, increase the salt content /slowly/, you don't want to stress already sick fish.

2. Increase the temperature to 80F:  Again, do so slowly, upping it about 2 degrees a day, again, don't stress the fish.  Keep an eye on the fish and make sure that they don't show any additional stress.

3. Medication.  I like the Mardel line of products, but there are many different kinds of Ich medication.  Check with your local fish store for a product and /follow the directions/.

It is widely believed that Ich is always present in the aquarium and that stress caused by poor water quality and or harrassment by other fish leads to the onset of the disease.

I keep African cichlids and I always keep a certain amount of salt in my water.

I run with 1/4 cup per 10 gallons of Doc WellFish's Salt and 1/4 cup per 20 gallons of Instant Ocean.  This keeps the water to a decent GH as well as provides a good level of total dissoved salts that helps to keep infestations of many bacteria and parasites.

Of course, this is also because of my base tap water parameters, you'll have to experiment with the volume of Instant Ocean in your tap water to get the right GH.