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Marine Ich
Last updated on November 17th, 2023
What is Saltwater Ich - The Marine Ich Lifecycle
Marine Ich, or Marine Ick, is a small white, parasite that is known for killing saltwater fish. This illness is really a parasite that can be prevented!
Saltwater, or Marine Ich, is also known as "Cryptocaryon irritans" or "white spot disease". This parasite has 4 phases with known lifecycles. The ich parasite can sit dormant in the rock and sand, so even if you don't see ich, you likely have the parasite in your tank! There are ways to prevent marine ich from entering your tank, as well as removing it from your reef tank.
Table of Contents
The first stage when marine ich is noticed is known as the "Trophont" stage. This is the time when you see spots on the fish. The trophonts will burrow in to the fish, feeding on the fish for up to 9 days. You may not notice the parasite if it is focusing on the fishs' gills.
The next stage of the marine ich lifecycle is the "Protomont". This is the phase where the saltwater ich parasite drops off of the fish and swims for as long as 18 hours to find a surface within the tank where it can reproduce. This is the time when most believe they have cured marine ich. Unfortunatly, it is really when the ich parasite multiplies...
While reproducing the saltwater ich parasites are known as Tomonts and Tomites. The Tomont is the parasite that dropped of the fish to reproduce, and the tomites are the 200 or more children parasites it forms. These cells can incubate for anywhere from 3 to 72 days. This means your tank can have ich sitting dormant for 2 and a half months without food.
Finally, the Theront stage, is when these cells start the cycle again. Swimming freely in the water column for as much as 2 days looking for a fish to host. And it all begins again. This cycle can be as long as 84 days before the ich on an infected fish may multiply and attack again.
Saltwater Ich Treatment for Fish
When treating saltwater ick, you will need to treat the fish separate from the display tank system. Even fish that are not currently showing signs of saltwater ich could become sick at any time. It is especially common for the parasite to attack during times of stress. By treating all of the fish as if they were sick means that it will remove any parasites and illness that the fish may have. There are a number of ways to treat saltwater ich. Here are some of the most common.
Freshwater Dip
Using a Freshwater Dip is a frequently discussed saltwater ich treatment in reef tanks. This method includes removing the fish from the reef tank, and dipping them in fresh water for no more than 5 minutes in well airated, heated RO water. This method is used to help reliev saltwater ick from the fish, however it will not work as a long term saltwater ich treatment. The best case scenario is that the saltwater ich on the fish dies, but it is still in the aquarium. So it may be gone for a while, but it will come back.
Hyposalinity for Saltwater Ick
Hyposalinity, also known as Osmotic Shock Therapy (OST), is a well known saltwater ich treatment. Hyposalinity is an especially good saltwater ich treatment for sensitive fish. Hyposalinity is defined as a specific gravity of 1.010-1.013 (salinity of 13-17ppt). Saltwater fish can live in this salinity level, but saltwater ich cannot.
Unfortunately, Coral and invertebrates also cannot live in hyposalinity. This means, like most saltwater ich treatments, that if you have a reef tank, you will need to remove the fish completely and use a quarantine tank. If you have a FOWLR tank though, you may be able to use hyposalinity in your display system itself.
Hyposalinity works because saltwater ick cannot regulate the cell walls with the change of salinity. This causes the saltwater ick parasite to essentially explode. Some species of saltwater ick have been known to survive through hyposalinity. That being said, you can use hyposalinity in addition to another saltwater ich treatment and handle a wide variety of illnesses at the same time.
Unless hyposalinity is maintained in the display tank, the saltwater ich on the fish in quarantine will die, but it is still in the aquarium. So it may be gone for a while, but it will come back. Holding hyposalinity in the display tank is a valid saltwater ich treament, but it will kill most invertebrates, corals, and can affect your biological filtration. As such, it is best to only use hyposalinity in quarantine tanks.
Treating Saltwater Ich with Copper
Copper is a common saltwater ich treatment, however it is toxic to reef tanks. Copper will kill invertebrates such as snails, hermit crabs, shrimp, and even anemones and coral. It may seem like an acceptable treatment in the main tank, as coral and invertebrates are easier to remove than fish. Unfortunately, this could mean never having invertebrates or coral again.
Many copper treatments will be absorbed in to the rock and/or sand. This means you should NEVER use copper in a reef tank, as it will leach out and can kill new additions. The solution? Quarantine Tanks. Using copper as a saltwater ich treatment in reef tanks requires that you move all fish, not just the sick ones, to a quarantine tank and treat the fish with copper there. This will prevent killing everything in your main tank.
When using copper as a saltwater ich treatment, you'll need to treat for a minimum of 2 weeks. You will want to quarantine all of your fish for 2 weeks after the last visible spots from saltwater ich disapear. The amount of copper you need in your quarantine tank will depend on the copper product you use. Copper Power is considered one of the safer copper treatments to be used with saltwater ich infected fish. The copper levels when using Copper Power is 5 times higher than the most popular product, Seachem Cupramine. Regardless of which copper solution you choose, make sure to follow the directions to keep your fish safe.
If you are looking for a good copper tester, without the color comparison guess work, check out the Hanna Instruments Checker Copper High Range Colorimeter.
Tank Transfer Method
Tank Transfer is a chemical free saltwater ich treatment in reef tanks. The concept is fairly simple but you will need at least 2 tanks. Unlike hyposalinity and copper treatment, this saltwater ich treatment focuses on moving fish from one tank to another timed to the different phases of the ich lifecycle. Essentially the concept is to move the fish to a new, clean tank as the parasites fall off. Then draining the old tank. Though this method works most of the time, it is possible for some of the parasite to survive as the premise is based on timing.
So how do you do the tank transfer method? It's quite simple really. To start, you will need 2 tanks with identical temperature and salinity. You will place all affected fish in the first tank. On the 3rd day (but no more than 72 hours), move all of the fish to the second tank. You will then turn off all equipment heaters and air stones, and completely drain the first tank, and rinsing it out. Then you will set it up identically to the other tank. On the 6th day (no more than 72 hours after the last transfer) you will move the fish to the other tank. You will repeat this for a minimum of 14 days, but ideally over 30.
I think it's obvious why this method isn't ideal. The water from the other tanks cannot be re-used, nor added to the opposite tank, as it could contain parasites. Additionally, you can't use filtration or sponges because the saltwater ick parasites could be living in them. Though this could be done by setting up 5 to 10 tanks. That way you can move the fish along. However you will still need to either drain and rinse each tank after the fish leave to the next, or let them sit empty for 30 days without fish.
Killing Saltwater Ich in the Tank (not on the fish)
As you likely read above, in "What is Saltwater Ich - The Marine Ich Lifecycle", the lifecycle of the Saltwater Ich parasite can last for up to 84 days. The unfortunate part is that the only times when saltwater ich can be treated are when they are in the water column or on the fish. But for the 3 to 72 days (you read that right) there is nothing you can do. This is why there is no great way to handle completely remove the ich parasite from the tank.
There are a few ways that can help you in either maintaining a low number of ich parasites, or possibly destroy them all!
Saltwater Ich Treatment in Reef Tank - Maintain Fallow Reef Tank
Starting with the only saltwater ich treatment in reef tanks to ensure total removal of the ich parasite. Keeping the tank fallow, meaning abosolutly no fish, for 90 days means the parasite will have no food and die. The reason for the 90 day time frame is that the marine ich parasite can live for 84 days, only a small piece of that is the time in which the parasite is infecting a fish. Assuming it is possible that some of the parasites are freaks of nature and live an extra couple days, the 90 day window should essentially guarantee success!
During this time, you can quarantine and treat the fish from the reef tank using 2 to 4 week phases of multiple treatments above!
There is some research showing that if you raise your reef tank temperature to 81F that the fallow period could be as short as 42 days. I would personally encourage waiting at least 50 days to be extra sure. This is just because I've gone through large losses with marine ich and wouldn't risk it for a quick fix.
Ultraviolet (UV) Treatment
Another frequently used saltwater ich treatment in reef tanks is the use of a UV filter. UV filtration, with a slow enough flow rate, can kill saltwater ick parasites. Unfortunately, this will not kill all of the marine ick parasites in the reef tank. The UV filter can only kill parasites that flow through the UV filter for enough time to kill it. It won't do anything for the parasites that are in the sand, on the fish, or in the water column and not passing through the filter. Though UV may slow down marine ich, it will not remove it completely.
Reef Safe Saltwater Ich Medication
There are some reef safe saltwater ich treatments on the market, such as Kick Ich. This solves all of the problems, doesn't it?! Don't get too excited. Though it is possible for the medication to work, it only affects ich in the water column. Making it nearly impossible to kill all of the marine ich in the tank. The cost of most of these medications can be fairly high if you have a large reef tank as well! If you have a reletively small, and simple reef tank setup, or don't have an easy way to set up quarantine tanks, it may be worth trying however.
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