Freshwater Ich
The ciliate,
Ichthyophthirius multifiliis,
is an obligate parasite that affects all species of freshwater fish, causing the disease ichthyophthiriasis,
which is commonly referred to as ich or white spot. I. multifiliis is one of the most prevelant protozoan parasites of fish and is an important pathogen of ornamental and farm-raised food fish species when reared under intensive conditions. Wild fish populations are also susceptible and outbreaks are occasionally seen. There are few aquarists that have not met it on one or more occasions[1]. The I. multifiliis life cycle consists of the free-swimming, highly motile infective theront, which is approximately 40-50 microns in length; the fish associated trophont, which grows up to 800 microns in diameter; and the reproductive trophont, which leaves the fish and secretes a gelatinous cyst, in which it undergoes 7-9 divisions to produce 800-1000 daughter tomites. Highly dependant on water temperature, the entire life-cycle takes approximately 7 days at 25 degrees C to 8 weeks at 6 degrees C. Marine ich is caused by a different ciliate, Cryptocaryon. Like other ciliates, I. multifiliis cells have a transcriptionally inactive germline micronucleus and a transcriptionally active somatic macronucleus.
Marine Ich Cryptocaryon irritans is a species of ciliate protozoa that parasitizes marine fishB, and is one of the most common causes of disease in marine aquaria.
The symptoms and life-cycle are generally similar to those of Ichthyophthirius in freshwater fish, including white spots, on account of which Cryptocaryon is usually called marine ich. However, Cryptocaryon can spend a much longer time encysted.
Infections can be extremely difficult to treat because of other creatures, such as corals and other invertebrates, which will not survive standard treatments. Ideally fish with Cryptocaryon are quarantined in a hospital tank, where they can be treated with a copper salt or using hyposalinity. The display tank needs to be kept clear of fish for 6-9 weeks, the longer the better. This gives time for the encysted tomonts to release infectious theronts, which die within 24-48 hours when they cannot find a host.
Cryptocaryon irritans was originally classified as Ichthyophthirius marinus, but it is not closely related to the other species. It belongs to the class Prostomatea, but beyond that its placement is still uncertain.
Useful treatments of Cryptocaryon irritans are copper solutions, formalin solutions, and quinine based drugs (such as Chloroquine
phosphate and Quinine Diphosphate).
By the way, I've decided to go with Copper (Cupramine) to treat my fish as I've discovered that Hyposalinity works but generally outbreaks will occur as it doesn't typically kill all. I trust Bob Fenner as a great source for information on care for my fish and that's where I got this bit of info, www.wetwebmedia.com
Added Cupramine yesterday and the spot seem to just disappear gradually. This morning they appear to be gone. I'll continue this process for the recommended treatment timeframe. 
