How to Deal with Marine Ich in the Saltwater Aquarium

Marine Ich is one of the most common diseases affecting saltwater aquarium fish and if you are not properly equipped with the knowledge to deal with an outbreak, the disease can spread quickly, infecting the other fish in your tank. Not only is Ich a quick-spreading disease but it can also be fatal if left untreated. If you want to keep your fish as healthy as possible you should take the time to learn the basics about what marine Ich is, how to treat it and how to prevent it. Prevention is infinitely more effective than treatment in terms of keeping your fish healthy.

What is Marine Ich?

Marine Ich is a disease affecting saltwater aquarium fish that is caused by the parasite Cryptocaryon irritans. This disease is also called Marine White Spot disease because it typically manifests in the form of small white spots on the gills, bodies and fins of marine fish. Marine Ich is very similar to freshwater Ich, or Ichthyophthirius, a disease caused by the parasite Ichthyophthirius multifiliis. Both parasites go through a similar life cycle beginning with the feeding and growing stage during which the parasite attaches itself to the host as a trophont, having the appearance of a small white spot. Once the trophont matures, it leaves the host and becomes a tomont which becomes encysted upon attaching to aquarium substrate or other tank surfaces. In cyst form, the tomont divides to produce up to 3,000 tomites which break out of the cyst wall and spread throughout the tank to seek a host body. The main way in which Marine Ich differs from freshwater Ich is that the Cryptocaryon irritans parasite stays encysted for a much longer period of time – up to one month. Once the cyst breaks open, however, both parasites spread rapidly throughout the tank, infecting whatever tank inhabitants they come into contact with.

Symptoms of Marine Ich

The most common symptom of Marine Ich is the appearance of small white spots on the gills, body and fins of infected fish. You should be aware that while all species of saltwater aquarium fish are capable of contracting the disease, some species are more susceptible than others. Surgeonfish, for example, are highly likely to contract the disease while sharks and rays have a lower susceptibility to Marine Ich. In addition to white spots, infected fish may also develop ragged fins, cloudy eyes or pale gills. Some fish experience an increase in mucus production or changes in skin or scale color. In some cases, infected fish may exhibit behavioral changes, becoming lethargic, swimming abnormally, rubbing against tank objects or breathing more quickly than usual.

Treating Marine Ich

Unfortunately, there are many misconceptions regarding the treatment of Marine Ich which leads many aquarium hobbyists to go through ineffective treatment regimens. Unlike freshwater Ich, Marine Ich is not sensitive to temperature changes so increasing the temperature in your saltwater tank will not help to speed up the lifecycle of the parasite. Neither will the addition of cleaner shrimp or fish to the tank be beneficial in removing the parasite from the skin of infected fish because the parasite will eventually burrow into the skin below the mucus layer where cleaner shrimp and fish cannot reach it. One of the most common treatments for Marine Ich in the saltwater tank is the addition of copper to the tank water at a rate of 0.15 to 0.24 mg/liter. This treatment is typically effective within 2 to 4 weeks but you should be aware that prolonged exposure to copper can be dangerous for fish and it may lead to increased stress. Another option is to increase the salinity of your tank to 11 or 12 ppt and to keep it at that level for 4 weeks after the symptoms have gone away. If you are able to catch the disease before it spreads to other fish in the tank, you might also try moving the infected fish to a hospital tank to administer your treatment.

Marine Ich can be incredibly tricky to treat because the cysts can remain dormant for such a long period of time. If you do not follow through with the proper treatment protocol, your tank could become re-infected as soon as the cysts break open and you will have to restart the entire treatment process. Your best bet is to keep the tank clean and to quarantine new fish to prevent an outbreak from happening in the first place but, if your fish do contract Marine Ich, it is important that you take action to begin a treatment regimen as soon as possible.