In 1977, I set up my first marine aquarium. In those days, there was no live rock or even aragonite substrates so the method was very different from what we use today. The typical setup included crushed oyster shell or dolomite for gravel, placed over an undergravel filter (Nektonics ruled back then) using 1-inch lift tubes driven by limewood air diffusers. If you had the money, you would get a canister filter and have a really sweet setup. Lighting was standard T12 fluorescent fixures with daylight bulbs (5000K).

Like most beginners, I had no idea what I was doing, and I really didn’t want any advice from anyone. I figured, how hard can this be? Shortly after my very first setup was complete I fully stocked the tank. I got Ich.

I watched all the fish die.

That was 30 years ago. On a recent trip to a local LFS, I purchased a Pearly-Scale Butterfly fish. After being placed in my quarantine tank, I noticed it definitely has Ich. Fortunately, I’m a lot smarter now and the fish was promptly treated, released from quarantine, and has been doing fine in a community tank ever since.

Marine Ich has been running rampant in this hobby for at least 30 years, perhaps much longer. Surely in this amount of time the importers, the exporters, industry support groups, or even LFS’s would have gotten together and figured out how to wipe out this parasite from the supply chain. But they haven’t. It keeps propagating (and surviving) from the South Pacific holding tanks to your living room aquarium. There are procedures such as dips and medications that can stop Ich in its tracks. But this doesn’t look like it’s going to happen anytime soon. The ornamental marine business is a rag-tag industry of rogue fish collectors and corrupt, unregulated island-countries. When clownfish sell for $0.03 each at the dock, there isn’t much incentive to install treatment facilities. The bottom line is that it is your responsibility to deal with Ich on any fish you buy.

Do not think for one minute that a fish with clear fins in your LFS’s tank does not have Ich. The parasite normally attaches to the gills first, which cannot be seen. And not all fish scratch when infected with Ich. Many LFS’s use copper in some or all their fish holding tanks. This is an excellent measure to minimize the spread of the disease, but it does not necessarily prevent the parasite from coming home with you. First off, the copper concentration may have drifted below its therapeutic level. the knee at which copper kills the parasite is very slim. Secondly, it takes at least 7 days for attached cysts to dislodge. If the fish hasn’t been at the LFS very long, the copper won’t have enough time to work.

I don’t know what the odds are of buying a fish today infected with Ich, but talking with fellow aquarists across different parts of the country, the consensus seems to be approximately 2 out of every 3 fish either have Ich or a related life-threatening parasite (i.e. Oodinium) when purchased. Folks, this is an epidemic. If this was happening to humans, the world would be in deep shit. Such a statistic makes cancer and heart disease look like the common cold.

So here is my (and your fishes) survival guide on how to beat Ich and get it out of your house once and for all. First, Let’s review some myths and truths:

(1) Ich is always present in an aquarium- WRONG. Ich doesn’t come in with dry salt mixes or lands in your tank from the atmosphere. Ich is a single-celled animal that is introduced to your tank, usually attached to a new fish or free swimming in the shipping bag water.

(2) Ich cannot be killed or completely wiped out- WRONG. Ich is an Obligate Ectoparasite. This means that without a host (a fish), it will die of starvation within 6-8 hours.

(3) Cleaner Wrasse (Labroides Dimdiatus) and Cleaner Shrimp (Lysmata Amboinensis) eat Ich- WRONG. Wrasses and shrimp eat necrotic tissue, damage scales, and scabs. It has been well documented that the symbiotic “cleaning stations” in the reefs by wrasses and shrimps are there to help heal wounds from carnivore attacks, territorial fights, and other skin/scale injuries. It is possible that these cleaners might knock the parasite off the fish while doing this, but do nothing to control the reproduction and life cycle of Ich in your aquarium.

(4) Fish eventually get immune to ich- TRUE. After repeated exposure and survival, fish build an immunity to Ich. However, new introductions don’t have this immunity and often die of Ich within a week of introduction, even though every other fish is fine. You will blame your LFS for selling you a fish with Ich, but the problem is Ich is present in your tank and your fish have gained some immunity which prevents fatalities- but they still suffer from the disease.

(5) Stress causes Ich- WRONG. If Ich is present in your tank then stress reduces immunity and your fish will show more advanced and serious signs of the disease. But if Ich is not present, it doesn’t matter how stressed your fish get they won’t get Ich.

(6) Freshwater dips eliminate Ich- WRONG. Freshwater dips may cause gill attached parasites to dislodge, but do not effect epidermal parasites. These are protected by the fishes own mucous layer. You may reduce the discomfort of scratching, but you will not prevent the cysts on the skin from dropping off and reproducing in the gravel.

Life Cycle of Ich

Before I cover how to kill them, let’s look briefly at how they live:

• Free Swimming – The Ich parasite swims around your tank looking for a host. If it can’t find a fish within 6-8 hours, the parasite dies of starvation.
• Attachment – It finds a fish and attaches to the skin or gills. It stays put and feeds off the fishes body fluids for 4 days.
• Encystment – The parasite is now nourished and encased in a hard shell. It drops off the fish. The cyst floats around the aquarium for up to 18 hours looking for a place to settle down.
• Reproduction – Once settled in, the cyst begins to reproduce (by cell division) splitting about 9 times which produces roughly 500 baby parasites within the cyst. This can take up to 28 days.

When the cyst breaks open, all the parasites start swimming around looking for a host, and the cycle starts over again.

Treatment and Elimination

The only time you can kill Ich is when it is swimming around. When it is inside the cyst or attached to a fish, no medication or method can be used that would be equally harmful to the host fish.

First thing you need to do is remove ALL fish from the aquarium, including those that do not show any signs of the disease. Put them in another aquarium with established biological filtration. Purchase a copper treatment (such as Seachem Cupramine) and follow label directions.

Keep your display tank fallow (without any fish) for 31 days. There is new evidence that suggests raising the temperature of the display tank to speed the life cycle of the parasite is a bad idea. This will cause some  cysts to go into a long stasis period, perhaps several months. So do not raise the temperature of the display tank. Public aquariums go 6 weeks to ensure resistant strains are fully wiped out.

After 31 days (or longer), return all the fish to the display tank. The copper treatment in the holding tank should have killed any parasites that were on the fish when originally transferred.

That’s it. You’re done.

Ich has gotten so bad the last few years that I now recommend a prophylactic copper treatment for at least a month on all incoming fishes. For me, the hassle of removing fish from the display tank far outweighs the inconvenience of a 30 day quarantine.

Finally, this question always come up, ” What about the reef-safe medications I can buy?”

There is no such thing as a 100% effective reef-safe Ich medication. These products are marketed to prey on the aquarist’s anxiety and fear of having to catch and remove fish from a reef tank. The metradinazole-based medications (Ruby Kick-ich, Flagyl) works great for freshwater icthyphonus but does nothing in saltwater. Pepper-based products (Kent RxP) that cause sloughing of mucus makes the spot go away and the fish looks better. But the cyst will still hatch 2 weeks later and the infestation starts over again. Garlic and other herbal immune system boosters are at best, anecdotal. Copper is the only proven medication with a 50 year track record of a 100% kill of parasites.

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