White Spot (Ich)-

Scientific Name: Ichthyophthirius multifiliis (causative agent)

Distribution : Worldwide, in fresh and brackish water

Causes :
Abrupt fluctuations in temperature especially a fall in temperature can cause an outbreak of Ich. Increased ammonia and nitrate levels also promotes the disease.

Infection Symptoms :
Non-feeding, hiding abnormally, itchiness with rubbing & scratching , surface breathing and rapid respiration. Most obvious are the presence of white spots (about 1mm) all over the body and fins.

Treatment :
The treatment prescribed varies depending on the mass of the fish, the fish general tolerance towards temperature changes and depending on the stages of the infection. The most general medication used is Malachite Green (available commonly) and the dosage is normally about 0.1mg/Litre of water. It's best to separate the infected fishes in another empty tank with similar water pH and temperature when applying the medication. When treating the main tank, remove any carbon filters used so that it does not absorb the medication. Change the water every 10-12 hours and repeat the medication gradually for up to 3 days. A salt bath will also be helpful, especially for heavily infected fish.

Note : some scaleless and smaller fishes may not be able to tolerate similar dosage for larger fishes, it's best to reduce the dosage to half (read the medication instruction carefully, the dosage recommended may vary).

If the fish can tolerate higher temperature conditions, one can also try to increase the temperature of the tank (must be done gradually) up to 81-82 degrees F. This will help to "kill" the causative agent which are very sensitive to higher temperature especially in the later stages of the infection cycle as well as speed up the life cycle of Ich. The higher temperature condition should be maintained for at least 2-3 days.

Copper (at 0.25 mg/L) is most often used in marine systems, but it may be less effective and more toxic than malachite green or formalin/malachite green mixture. Copper should not be used on freshwater fishes.

Disadvantages of treatment chemicals:
Copper - toxic to freshwater fishes
Methylene Blue - harmful to plants
Formalin - kills beneficial bacteria
Malachite Green - carcinogen

If you fish is sensitive to chemicals, see the alternative method to treat ich.

Note:
Do not treat treat only the infected fish. The whole tank should be treated.
To be on the safe side, treatment should take place for approximately 3 weeks. (This is because the parasite can stay in a host for up to 2 weeks. The parasite will leave it's host to begin its life 'cycle'. This cycle is where it reproduces. It will find a quite area and attaches itself to an object where it will then divide up in two, then, four, eight and so on until it reaches thousands of cells, this can take between 8-24 hours. The cells are released into the water to find a new host. If one is not found they will die within 48hours. Once a host is found the infection starts all over again. A parasite inside a fish cannot be killed, they are only vulnerable during the cycle period whilst they are free swimming. This is where treatment will work. It is also good to note that the higher the temperature the faster the cycle, so the more effective the treatment. )

After surviving an infection the fish are, to a certain extent immune to further infection. The parasites then form a latent stage at protected sites such as gills or fin bases. Subsequent stress, poor conditions or transfer causes these stages to reactivate and attack the same of newly introduced fish. Thus making fishkeepers think that the new fish has introduced the virus. The truth being that the new fish not being immune to the parasites can become affected.