Treating Marine Ich Featured

Marine Ich is a very different problem than Ich in freshwater tanks. Because the parasites spread quickly, it is important to treat your tank as soon as possible.

marine aquarium Marne tank

If you are an experienced aquarium hobbyist, you have probably dealt with your fair share of Ich outbreaks. What you may not realize, however, is that there are significant differences between freshwater and marine Ich. Both diseases are caused by a parasite but they can affect your tank and spread throughout your aquarium in different ways. If you have a saltwater tank, it would be beneficial for you to learn the basics about marine Ich so that you are prepared to deal with it, if needed


While freshwater Ich is caused by the parasite Ichthyophthirius multifiliis, marine Ich is caused by the parasite Cryptocaryon irrita. Like freshwater Ich, marine Ich typically manifests in form of small white spots covering the bodies, fins and gills of saltwater aquarium fish. These spots are actually encysted parasites and, while attached to the bodies of fish, they are feeding on the fish in preparation for the next stage of their life cycle. Though white spots are the most obvious symptom of marine Ich, this disease may also cause fish to develop cloudy eyes, pale gills or ragged fins. In response to the parasite infection, some fish may experience an increase in mucus production on their skin which could also contribute to a change in skin coloration. In addition to these physical symptoms, fish may also exhibit behavioral changes such as lethargy, abnormal swimming behavior, labored breathing or rubbing against tank objects (flashing).

Transmission and Spread

Marine Ich has the potential to spread very quickly throughout the saltwater tank. By the time you notice the symptoms of the disease, the parasite may already be widely distributed throughout the tank. When the parasite is attached to the host body it is in the feeding and growing stage and, in this stage, it is called a trophont. Once the parasite matures, it detaches itself from the host body and becomes a tomont. During this stage, the parasite will attach itself to the tank substrate or other tank objects and form a cyst. Inside this cyst, the tomont divides up to 10 times, producing many tiny tomites which will eventually break out of the cyst and infect the entire tank, seeking host bodies to attach to in order to restart the entire life cycle. Unlike freshwater Ich, marine Ich is not affected by water temperature. A common treatment for freshwater Ich is to increase the tank temperature in order to speed up the life cycle of the parasite so that it becomes vulnerable to medication. Marine Ich, however, is not sensitive to temperature and it is likely to spread quickly in tanks that have poor water quality.

Treatment Options

The most common treatment for marine Ich is copper or copper sulfate. To administer this treatment properly, dose your tank at a rate of between 0.15 to 0.24 mg/liter. In most cases, this treatment is effective within a few weeks – do not prolong the treatment more than necessary because excess exposure to copper can be harmful for fish. Another option is a medication called Coppersafe which is a stabilized form of chelated copper that is safe for both freshwater and saltwater aquarium fish. This medication is effective against several kinds of external parasites and one dose lasts for 4 weeks. As an alternative to copper treatment, you could also try raising the salinity of your tank to 11 or 12 ppt. Be careful when using this treatment, however, because some fish may be sensitive to changes in salinity.

In addition to treating the infection, you may also want to take steps to improve the water quality in your tank. Fish become stressed when the water quality in the tank declines and that stress often results in increased susceptibility to disease – the happier your fish are, the healthier they will be. A simple way to improve the water quality in your tank is to add an EcoBio-Stone. These stones are made from volcanic stone and they are infused with beneficial bacteria. Once added to your tank, the beneficial bacteria from the EcoBio-Stone will rapidly multiply, working to maintain the nitrogen cycle in your tank, thus keeping your tank water clean and clear.

Leave a comment

Make sure you enter all the required information, indicated by an asterisk (*). HTML code is not allowed.

Subscribe to us for more aquarium set-up solutions!
Please wait

News & Media