If some morning you get up and it looks like someone has salted the body, fins, and gills of your fish, you are looking at Ich, sometimes called Ick, or white spot disease. Ich is a protozoan parasite with the scientific name of Ichthyophthirius multifiliis. It is the largest of the ciliated protozoans. It is easily introduced into your tank by new fish or equipment or plants that have been moved from one tank to another. A quarantine tank is the best way to prevent introducing this parasite into your display tank. If you see ich on your fish they should be treated immediately. In heavily stocked tanks it can cause massive death rates within a very short period of time.
Some symptoms before white spots appear may include flashing, clamped fins, weakness, loss of appetite, and decreased activity. In the case of heavy gill infestations, you may not see evidence of white spots, but may find your fish breathing heavily at the surface of your tank. Secondary bacterial and respiration difficulties may result, so keep an eye out for complications in addition to the ich infection.
The best way to prevent ich, as I stated above, is to quarantine all incoming fish. A minimum of four weeks in quarantine is the best way to go. When kept at 76 to 83 degrees, incoming fish that have been exposed to ich may show symptoms within the first 3 days. However, at cooler temperatures, ich outbreaks may take longer to show up because of its lengthened life cycle. Water temperature has a tremendous effect on how fast the life cycle of ich is completed. At water temperatures of 75 to 79 degrees F, the life cycle is completed in about 48 to 72 hours. In water temperatures below 75, it takes much longer for the parasite to complete its life cycle.
There are three phases to the life cycle of this protozoan. Ich is susceptible to treatment at only one stage of its life cycle, so knowing the life cycle is important.
- Adult Phase: The parasite attaches itself under the mucus layer of the skin or gills, causing irritation and the appearance of small white spots. As the parasite matures, it feeds on blood and skin cells. After some time, the parasite breaks through the mucus layer and falls to the bottom of the aquarium.
- Cyst Phase: After falling to the bottom of the aquarium, the adult cyst bursts and divides into numerous daughter cells called tomites.
- Free Swimming Phase: After the cyst phase, the free swimming tomites search for a host. If a host fish is not found within 2 to 3 days, the parasite dies. Once a host is found the whole cycle begins again. These three phases take about 28 days at 70 degrees F but only 3 days at 80 degrees F. For this reason it is recommended that the aquarium water be raised to between 80-86 degrees F. for the duration of the treatment. If the fish can stand it, raise the temperature to 86 degrees. Raising the aquarium temperature in this manner will shorten the length of time between the cyst phase and the free swimming tomite stage. It is during the free swimming tomite stage that chemical treatment is effective in killing the parasite. During this time, whatever you use for treatment should be supplemented with daily or every other day water changes and gravel vacuuming to remove as many adult cysts and free swimming tomites as possible.
Before starting treatment you should do at least a 50% water change and vacuuming of your tank. I also suggest doing 50% water changes every other day of treatment, to reduce the number of parasites in the water.
I do not like to use medication with my puffers, except in cases of heavy infestation. Melafix is helpful to treat any damage done to the puffer’s skin from the parasite. If you run into any severe secondary bacterial problems, Pimafix may also be used.
For freshwater puffers, it is recommended to use 1 tablespoon of salt per 5 gallons of aquarium water, while gradually raising the temperature to 86 degrees F. Continue with this for a period of one month, adding back 1 tablespoon of salt for every 5 gallons of aquarium water that you remove during water changes.
One thing to remember with high temperatures is that there is less dissolved oxygen available in warm water than there is in water at cooler temperatures, therefore it is recommended to run an additional airstone to oxygenate the water.
For saltwater puffers with Ich, you may wish to consult this article regarding it’s treatment.
(Co-authored by Dawn R)