White Spot Disease, also known as Ich or Ick, is a very common problem in aquariums and several different methods of treating it has been developed. In this article, we will take a close look at salt and malachite green. If salt or malachite green is the best available treatment for your particular aquarium depends on several different factors, including which species you keep and how sensitive they are to salt. Salt as well as malachite treatment is often combined with an increased water temperature and added aeration.
Malachite green treatment
Malachite green must be accurately dosed since it is a powerful chemical that will kill you fish if you overdo it. Some species are less tolerant to malachite green than others and it is therefore a good idea to research your species to find out how much malachite green they can handle. Many manufacturers recommend one drop of their product for each gallon of water in the aquarium to treat White Spot Disease, but a lot of producers sell really concentrated malachite green where one drop/gallon will not be safe to use on sensitive fish species.
A dose of 0.05 milligrams malachite green per liter water is generally considered safe when used for three successive treatments (one every other day) but calculating it can be a bit tricky since different bottles contain different concentrations of malachite green. Look for the concentration listed on the bottle of the medication. It will normally be in percent, so you need to convert it into milligrams per milliliter. 1 percent equals 1 gram per 100 milliliters of water. A 0.5% malachite green solution will for instance contain 5 mg/milliliter. The recommended dose written on the bottle is often 1 drop per gallon (in the U.S.), and since 1 milliliter is about 15 drops, such a dose will create a concentration much higher than 0.05 milligrams per liter. This is why many aquarists have such bad experiences from malachite green; if you follow the dose recommended by the manufacturer you will often overdose and harm sensitive species. If you purchase a 0,75% malachite green solution, add no more than 4 drops per 10 gallons of water.
Marine salt treatment
The Ich parasite does no like salt and using aquarium or marine salt is therefore a good way of getting rid of it, provided of course that you keep fish species that can tolerate the increased salinity. The high salinity should be maintained for two weeks to be sure that all parasites are really gone. Bringing the salinity up to 5 ppt (parts per thousand) will kill nearly always kill the parasites, but may be too strong for salt intolerant fish. If you keep catfish or equally sensitive species, bring the salinity no higher than 2 ppt and hope for the best.
Temperature and aeration
The use of malachite green or salt is often combined with an increased water temperature when combating White Spot Disease, sine this speeds up the life cycle of the parasite. If you decide to boost up the temperature you should ideally also provide additional aeration since cool water holds oxygen better than warmer water. The increased water temperature will simultaneously increase the metabolism of your fish, which in turn increases their need for oxygen. Since Ich parasites frequently attached themselves to the gills of fish and destroys them, it is easy to understand that an increased water temperature can be very difficult for the diseased fish to handle. Adding additional aeration and keeping the oxygen levels really high will aid them in their struggle. source:http://www.aquaticcommunity.com/disease/whitespot.php