The fish disease Ich or Ichtyopthirius is the most common aquarium disease. Ich is a parasite that attaches and feeds from your fish. It looks like little white dots, like grains of salt, all along your fish and for that reason is sometimes referred to as white spot.

The Lifecycle of Ich

Like any other parasite, Ich has a lifecycle and is thought to have a lifespan of about 2 weeks. The white spot disease that you see on your fish is Ich in it’s adult stage and ready to make more little Ich’s.

Once it is done feeding on your fish, it drops off and is “free swimming” where it makes it’s way to the bottom of the tank and attaches to your decorations and gravel. Of course it is very hard to notice there so many fish keepers don’t even realize that it is hiding on the bottom waiting to make more trouble and disease for your fish.

Once it’s settled in at the bottom, it starts to multiply. It just starts dividing itself into other Ich’s and I am told it can multiply up to 2000 times! These little “baby Ich’s” are called Tomites and this whole process will happen faster in warmer tanks than in colder ones.

Once the Tomites are developed, they become “free swimming” and are called Theronts – they swim around looking for a host fish. Once they find a victim, they attach themselves (once attached they are called Trophozites) and start the cycle all over again.


Ich can only be treated in the free swimming stage so water changes can help even if you don’t see them swimming around (if they are on your fish, there are also some swimming around in the tank). Of course, this isn’t going to get rid of all of them, and it’s probably not good to do too many water changes in a short period of time so other treatments for this fish disease should be considered. Obviously, you want to start treating the tank as soon as you see this disease start.

Raising the temperature in your tank will help speed up the life cycle process of Ich and accelerate your treatment. This is not viable for all tanks as some fish like goldfish can not tolerate warmer waters. In any event a temperature above 82 degrees F is not recommended.

Some people recommend to treat Ich with salt – there are products in your pet store or here online for this. Salt is also recommended for treatment of other disease and sometimes as a maintenance routine but I would be cautious of using it as it can be harmful to some fish like catfish, tetras, cordydoras and other scaleless fish.

Finally, you should treat for Ich with special products made for such occasions such as . Follow the directions on the package but remember to keep treating the tank for 3 or 4 days after you no longer see the parasites on the fish. This will help insure that any free swimming forms are killed as well.