Marine Ich

Marine Ich (Cryptocaryon irritans) is a common fish parasite similar to Freshwater Ich (Ichthyophthirius multifiliis). Not to be confused with Marine Velvet Disease (Amyloodinium ocellatum).

File:Yellow tang ich.jpg

Yellow tang infected with marine ich

Symptoms

• Usually appear as salt or sugar-like “sprinkles” on the body & fins. If the sprinkles are too numerous to count it is possibly Marine Velvet (Amyloodinium ocellatum).
• Flashing, scratching, twitching and heavy breathing are other possible indicators of ich as sometimes the parasite can harbor inside the gills.
• Swimming abnormally or staying near the surface.

Causes

Contrary to popular belief, ich is NOT present in every tank. It must be carried in by an infected fish or on contaminated substrate, coral, rock, equipment, or water. Improper quarantine is the main cause of ich. The parasite will then attack the fish and become visible to the naked eye as "sprinkles" when fish become stressed for any reason, or when the parasites increase in numbers

Life Cycle

Understanding the parasite's life cycle is critical for treatment. The life stages are as follows:

Trophont Stage

The “feeding stage” of the parasite that attaches itself to the fish, commonly associated with salt or sugar-like “sprinkles” on the body and/or fins. These sprinkles are not the actual parasite, but are the fish’s immune response to the parasite. Each white dot is caused by excess mucous which forms around the area where a trophont latches onto the fish. White spots are not always visible when a fish is infected with ich, as the gills (which are out of sight) are easier for trophonts to penetrate. Trophonts in the gills cause excess fluid to build up, making it more difficult for the fish to breathe. This stage lives from 3 to 7 days.

Protomont Stage

The life stage after a trophont drops off the fish, before becoming a tomont. Protomonts crawl around looking for hard surfaces to encyst upon so that it can form itself into the Tomont or reproductive stage, which can take up to 18 hours.

Tomont Stage

This is where the parasite forms a membrane while attached to the substrate and goes into its reproductive mode, this can take from 3 to 28 days depending on the temperature of the water.

Theront Stage

The “free swimming” stage which seeks out fish to infect. Theronts are the only life stage susceptible to chemicals (e.g. copper) and hyposalinity. It is also possible to cross contaminate with theronts by sharing water between tanks or via aerosol transmission. Once a theront finds a fish and attaches, it becomes a trophont and the life cycle begins anew. It only has between 24 to 48 hours to do so or else it will die.

Treatment

For a newly acquired fish in a quarantine tank:

Proceed to “Treatment options” below.

For infected fish in the display tank:

There is no easy way of dealing with this. Most corals/inverts are intolerant of chemical treatments (e.g. copper, chloroquine) or hyposalinity. Even in fish only systems, it can be problematic trying to treat in a display tank environment. Copper (and other medications) can be absorbed by rock, and doing hyposalinity risks possibly wiping out biofiltration (beneficial bacteria). Your best option is to catch ALL of your fish, and quarantine using one of the treatment options listed below. The display tank itself should be left fallow (fishless) for 6 weeks at 80.6°F (27°C) to starve out any remaining parasites. If ich eradication is not an option there is ich management which involves keeping the overall number of parasites down, while simultaneously boosting the fishes’ immune systems. See "Ich Management Methods" below.

Treatment Options:

• Chloroquine Phosphate
• Copper treatment
• Hyposalinity
• Tank Transfer Method

Ich Management Methods

• Utilizing the biggest UV sterilizer you can fit/afford. UV will keep theront numbers down so the fish can better cope with the ones remaining. A diatom filter can also be used to remove free swimmers.
• Boost your fishes’ immune systems through proper nutrition. This means feeding a wide range of live & frozen nutritious foods, not just flake & pellets. Feed nori, as that is loaded with vitamins. Also, soak fish food in vitamin supplements such as Selcon, Zoecon and Vita-Chem to further enhance health. Omega 3 & 6 fish oils are great (and cheap) soaking alternatives.
• Stay on top of your aquarium husbandry. Maintain pristine water conditions, stable parameters and avoid fish that are likely to fight. Poor water quality, fluctuating parameters and aggression from other fish will stress other fish, lower their immune systems and make them more susceptible to parasitic infestation.
• Choose your fish wisely. Avoid “ich magnets” i.e. fish with thin mucous coats such as tangs. Clownfish, anthias, wrasses and even mandarins are better choices as those have thick slime coats protecting their skin from attacking parasites. Also, only buy from reputable sources, and don’t buy fish that look diseased/damaged, won’t eat or who share water with diseased fish.

Prevention

Like most fish diseases and parasites, marine ich can be prevented by proper quarantining. To learn how to setup a quarantine tank see Quarantine Tanks.