If you’ve kept fish for any amount of time, you know the story: you look into your tank one day and you see it. The white spots. Maybe it’s only one or two on a single fish’s fin, maybe it’s coating every fish like they’ve been rolled in table salt. You have Ich in your tank. Now what?

First, don’t panic. Let’s learn a bit more about your foe before we discuss how to beat it.

Ich (Ichthyopthirius multifiliis), also known as White Spot Disease, is actually a parasite which can be transmitted to your tank from equipment, plants, or stock that is carrying the parasite, even without showing symptoms. Some in the fish keeping community even believe ich is present in any tank that holds fish. Either way, once it finds its way to your tank, you will want to act fast.

Thankfully, treatment is usually effective, but you need to be prepared for a few days to over a week of treating the affected fish and water.  and you will have to treat the water, as Ich has three distinct forms.  The parasitic trophont stage is what you see on your fish, the raised white cyst containing the Ich.  Once it has fed off the host fish, the cyst drops off and becomes the reproductive tomont stage, falling to the bottom of the tank and dividing into multiple cells which eventually burst and scatter through the water column as the infectious theront stage.  The entire life cycle of Ich, from when you first see it on your fish to when it becomes infectious once more lasts about 6 days at the average aquarium temperature of 78 degrees . If you don’t stop the cycle, it will continue to reinfect your fish.  Quick action is best to save your fish the pain and discomfort of the ich infection.

So now you act.  Assume that if you see one fish infected with Ich in your tank, all of the fish have it.  Some Ich infections are only in the gills and never show any signs on the body of the fish.  Better safe than sorry.  Treating Ich is relatively straightforward, but there are a few things you can do individually or in tandem with other treatments.  The easiest treatment method is to buy an Ich treatment from your local pet supply shop. Most are made with formaldehyde, malachite green, or copper sulfate, or a combination of these ingredients.  My personal favorite treatment is Hikari Ich X.  It is safe for most fish and invertebrates and more gentle than some treatments. Remove any charcoal filtering from your tank before adding any medications.  

It is recommended to slowly increase the temperature in your aquarium to 86 degrees over the course of a day to speed up the life cycle and reduce treatment times.  Some aquarists use only heat and salt, but this method is much slower than using a chemical treatment and cannot be used if you have any live plants in your tank.  It is always best to treat your tanks for at least one additional day after you have seen the last spots on your fish to be sure the parasite has been eliminated. After treatment, return the charcoal to your filter (if using) and do a partial water change, being sure to try to clean the gravel to remove any reproductive tomont that might remain.

That’s it!  You’re done!  And, as an added bonus, studies have shown that fish who survive an Ich infection show full to partial immunity to further infections.  But of course, as with all aquarium illnesses, prevention is the best action.  Please remember to quarantine all new fish for one week to monitor for signs of illness before adding them to your tanks. But if stress causes an outbreak or a new fish escapes detection and you find Ich in your tank remember not to panic.  Ich is not a death sentence.  And if you’re in the hobby for any amount of time, you will have to deal with it at some point. 

Now you’re armed with information on how to do it!