How To Treat and Prevent Ich in Freshwater Fish

How To Treat and Prevent Ich in Freshwater Fish

Ich is one of many common diseases found in freshwater fish, but not many people know what it is or how to treat it. The symptoms can be unnerving, especially when they begin to quickly spread from fish to fish and take over your tank. Learn how to treat and prevent ich in freshwater fish so that you can make sure this parasite never comes back.


Because the protozoa parasites that causes ich are so common, most fish have developed immune systems that can fight them off. However, when fish are stressed for any reason, their immune systems lower, making it harder for them to fight off common diseases.

This parasite often shows up as white spots on the gills or body of a fish, making it look like the fish is twitching when really they’re just itchy and agitated. If left untreated, it can cause loss of appetite, respiratory distress, and eventually death. If you’re unsure whether a fish in your tank has ich, a veterinarian can scrape a lesion and identify it under a microscope.


Because you’ll have to treat the entire tank if a case of ich is present, preventing ich from forming in the first place is much easier than treating the disease. Ideally, you never want to buy a fish with dead tank mates or a fish with any signs of disease. In addition, regardless of whether or not they look sick, you should quarantine any new fish for two weeks before official tank introduction with other tank mates. The same goes for adding new plants.

And as with any tank, maintain regular water changes and test the water regularly for pH levels, ammonia, and nitrate levels. Finally, never overcrowd your tank, and make sure you always store food correctly, ideally frozen.


Any mature parasites will fall off your fish within a few days. So the fastest way to get rid of the parasite from the tank is to remove all your fish, put them in another tank, and treat the infected tank by bumping up the temperature to 80 degrees for four days, which speeds up the immature life cycle of the parasite and kills it off.

There are plenty of ich treatments to treat your actual fish, or you can buy treatments from your local pet store to put in the tank water. Usually, these treatments will contain formaldehyde, malachite green, and/or copper sulfate. These ingredients may sound scary, but they won’t harm your fish.

Now that you know how to treat and prevent ich in freshwater fish, you’ll never have to worry about this pesky parasite hurting your fish ever again.

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