aqbannrm.gif - 4.02 K Aquarium
Copper: the Sure Cure for Saltwater "Ich"

"Ich"... what saltwater hobbyist hasn't one day noticed a fish or two scratching or breathing with difficulty, then seen the all-to-familiar little white spots begin to appear on the fins and bodies of his prized possessions? And what hobbyist hasn't lost fish, maybe by the tankful, to treatments that appear to provide temporary relief, but ultimately fail to eradicate this persistent pest?

It seems that new wonder cures for saltwater "ich" appear at least annually, to mixed reviews from both experts and hobbyists alike. While it is certainly hoped that one or more of these modern treatments will prove to be safe and effective, and simple to use as well, for now the treatment of choice appears to continue to be one that's been with us since the hobby's infancy: copper. To better appreciate why this is so, it's necessary to understand a bit about the disease itself.

The life cycle of the parasite Cryptocaryon irritans could almost be compared to that of the creatures in the "Alien" movies, in that there are three stages of development: a rather vulnerable infant stage whose only purpose in life is to find some poor sap to glom on to; a larger, more resilient and aggressive feeder stage; and an even larger and almost invulnerable breeder stage. Add a flamethrower-totin' heroine and some pyrotechnics, and you've got yourself a blockbuster movie.

OK, so maybe real-life "ich" isn't quite as dramatic as all that, but it's life cycle does contain three, very distinct, stages of development. Tiny infant "swarmers" ("tomites", if you really want to get technical about it) swim furiously around the aquarium, looking for a fish to call home. Those that succeed in finding a host burrow into its skin, feeding and growing to the point where they are visible as tiny white spots to the aquarist. These "feeders" (a.k.a. "trophonts") then fall off the fish and settle to the tank bottom, where they attach to some more-or-less inanimate object and begin cell division. After numerous cell divisions, the "breeder" ("tomont") cyst ruptures, releasing hundreds of new swarmers, and the cycle begins anew.

At any moment in time, an infected aquarium contains huge numbers of parasites in all three stages of development - and that is a major reason why most "ich" treatments (including some copper treatments) fail. The swarmers are relatively easy to kill with medications, but the feeders are buried in the fish's flesh and actually protected to some extent by the fish's own mucous secretions, while the breeder cysts are protected by their own hard shell. As such, a short-term treatment may well eliminate all the swarmers in the aquarium, resulting in a temporary reprieve - only to return like gangbusters in a few days, as the other two stages mature.

Plainly, a longer term treatment is necessary - a treatment that assures us that there will be a potent dose of medication in the water until every last parasite in the aquarium has gone through all stages of development and finally killed as a swarmer. But that presents the aquarist with a major problem: how to be confident that such a dosage is maintained, 24 hours per day, for up to the 14 or more days it might take for the last parasite to go through all its changes - and without risking overdosing the fish themselves. Drugs are absorbed, broken down, or otherwise neutralized at different rates in different tanks, and while adding x number of drops to y number of gallons every z number of days might result in a cure for one aquarium, it could easily result in an ineffective under-dose in another and a fatal overdose in yet another.

That's where copper treatments come in. Copper salts have long been the treatment of choice among many professionals, in spite of several drawbacks, specifically because the level of residual copper in the aquarium can be tested, and the daily dosage adjusted accordingly. The treatment level can then be kept quite constant in a range that is fatal to the parasite but not to the fish. Despite its flaws, copper is very nearly a "sure cure" - the one we want to use when we need to have the highest assurance of success.

Treating with copper isn't difficult, but it must be done correctly to be effective and safe. The first rule is one that hopefully most saltwater aquarists have already heard: don't use copper with invertebrates. Anemones, crabs, shrimp, live corals, "live rock" and all the rest of the non-fish critters we might keep in an aquarium are killed by copper just as easily as, although perhaps more slowly than, the invertebrate Cryptocaryon. Generally this means moving all the fish to that different, properly set up and conditioned "quarantine" tank we're all supposed to have in waiting. Removing the invertebrates to other quarters and treating the main tank is another option, but removing all traces of copper after treatment is such a time-consuming and unreliable process that it would probably be best to never return invertebrates to that main tank again.

The second rule is simply this: don't wait! Sometimes, ich will appear to go away with ineffective treatment, or even without treatment, as a wave of feeders fall off the hosts and sit invisibly on the tank bottom. The hobbyist breathes a sigh of relief, but a few days later, the fish are infested again, only at ten times the rate. Even the most effective treatment may fail at this point. Similarly, some hobbyist anguish for days as to whether to move the fish or invertebrates to another tank - only to have the decision made for them as the fish become unsalvagable.

The treatment tank can be the main tank, if the aquarist is willing to allow it to become a "fish only" tank from that point forward. But if not, it is important that the treatment tank include "all the comforts of home", including proper heat, filtration and suitable hiding places for the fish. Activated carbon and calcareous gravels both lead to copper loss and can either be avoided or used with the understanding that more copper will be needed. The tank must be fully through the Break-In Period and be of sufficient size to accommodate all the fish from the main tank for a month or longer. This is important because even a fish that appears to be uninfected might well harbor the parasites, allowing them to continue their life cycle. The cured fish will almost certainly become re-infected once they are put back into the original tank if the parasites are still present in quantity. The only way to be certain that an uncoppered tank is ich-free is if it has also been fish-free long enough for all the parasites to have become swarmers and starved before finding a host. In theory, this should be about 14 days, but this has not always been sufficient, so I'd recommend at least 28 days.

There are several forms and many brands of copper compounds available to the hobbyist. The simplest, and possibly most often recommended, form is commonly called "ionic" copper - and is little more than copper sulfate crystals dissolved in water. This can be easily manufactured at home or purchased as a prepared solution from the local pet store and is as effective as any other form. Unfortunately, copper sulfate has a propensity to precipitate out of solution rapidly or to "bind" to other ions in the water, especially in aquaria with coral or other calcareous rock or gravel, so it must be monitored very frequently (at least daily, twice daily is even better) and new copper added as needed. The target value for ionic copper is typically about .15 ppm.

To address the rapid copper loss problem, some manufacturers "chelate" their copper salt, which essentially means that the copper ion is bound to a larger molecule for stability. This process does seem to help keep copper levels in the treatment tank much more stable, but they still must be monitored regularly (preferably still daily) and replacement copper added as needed. Some authors believe that chelating drastically reduces the effectiveness of copper, citing the loss of positive charge of the copper ion that has long been held to be the reason that copper works in the first place. This is absolutely true in terms of dosage required to get the job done. Chelated coppers generally have a target value of 1.5 to 2.0 ppm or more (depending in part upon which chelating agent is utilized) - 10 to 15 times that of ionic copper. The manufacturers of these products, of course, look at this as a "glass is half full" sort of situation and claim that chelating allows copper to be used safely at 10 times its normal dose to really take care of those nasty parasites. I'm no expert on the chelation process, but there almost appears to be some sort of equilibrium involved, wherein a chelated copper concentration of 1.5 ppm yields an ionic concentration of about .15 ppm and the remainder stays bound to act as a reserve source of copper ions. My initial experience with chelated coppers had rather soured me on their use, primarily because their directions did not call for frequent testing of copper levels. I have since seen successful treatments in cases where copper was tested and re-dosed routinely.

Other manufacturers have created a sort of in-between product that is a bit more stable than ionic copper, but retains the positive charge of ionic copper, by means of an organic complex. At least one manufacturer claims that maintaining the positive charge not only increases the effectiveness, but also reduces the amount of copper taken in by fish, resulting in a safer product. I've personally had the most experience, and hence the most success, with these forms of copper. Again, copper testing and adding make-up copper should be done daily, but there is a little more margin for error or laziness than with ionic copper. The target dose is generally about .25 - .35 ppm.

Choosing a good copper test kit can be almost as involved and perhaps a bit more frustrating than choosing a good copper product itself. For starters, a kit that is meant for ionized copper may not work on chelated copper - even if it has the proper range. And speaking of range, if a kit's color chart jumps from .1 to .3, it is of limited value if your target range is .2. Finally, to mince a few words, there are many kits on the market that seem to have color charts that bear no relation to the colors that humans see when peering into those little glass vials. Best results can probably be had utilizing both treatment and test kit from the same manufacturer, or ask your local dealer what combination he uses. The store I manage has invested a couple of hundred dollars in a test system that uses a electronic colorimeter to give very accurate results, and I would urge other dealers to do the same and offer affordable copper testing for their clients, if not for daily checks, at least to check the veracity of their own test kits.

Regardless of which form of copper is used, it is best to start slowly if the tank in question has never been coppered before, since it can interrupt biological filtration, causing a rise in toxic ammonia and/or nitrite. I often recommend starting with half the manufacturer's suggested initial dose, added daily until copper tests begin reading near the target value. It is wise to test for ammonia and nitrite during the first few days of treatment, and treatment should be halted if their levels rise significant. Usually, treatment can be resumed after a couple of days, and no further problems occur in this regard.

The first copper test should be performed about 10 minutes after copper is first added to the aquarium. It is vitally important to determine how much a given dosage raises the copper level in the tank, and there's no better time to check it than when the initial tank level is zero. Let's say, for example, that 50 drops of copper treatment raises the tanks level to .1 ppm. You'll know, then, that if anytime in the future you need to boost the copper level by .1 ppm, you'll need to add an additional 50 drops. If you only need to boost it by .05 ppm, you'll add 25 drops, and so on.

Additional copper tests should ideally be performed every 24 hours, at approximately the same hour, immediately before the next dose of copper. I can't emphasize the importance of regular testing enough. If the copper level falls below its effective dosage - even for a few hours - some swarmers will survive, attach to fish, and the life cycle will continue, meaning you will need to continue treatment for two weeks from that point, regardless of when you started coppering. Immediately after the test is taken, additional copper should be added to return to the target dosage. Following the above example, if tests showed the copper level at .15, but your aim was .20, you'd have to add 25 drops of copper solution to the tank. Some hobbyists like to re-check the copper level ten minutes after each treatment, until they get more comfortable with the math.

If all goes well, fish start showing signs of improvement, including loss of visible spots, within a few days. It is important not to mistake this for a "cure" and get lazy about the treatment. Remember that Cryptocaryon is likely still present in stages that are not clearly visible. The minimum term of treatment should be 14 days, during which Cryptocaryon should have completed its life cycle and been eradicated, but for some unknown reason, even that is not always sufficient. There may be different strains of Cryptocaryon involved, or perhaps a few swarmers find a host too quickly to absorb a fatal dose of copper, and it takes several life cycles to eliminate them completely. At any rate, 28 days seems to be a more reliable course of treatment.

Sometimes it is necessary to tweak the dosage a bit, but again the reason for this isn't always clear. Some authors believe there are multiple strains of the parasite, some of which might require higher levels of copper, but it's also possible that the copper itself is somehow being bound up in the tank, or of course that the test kit is either failing or being mis-read. If the fish resume getting white spots, the level needs to be increased. This needs to be done slowly and carefully, of course, raising the level by no more than 20% at a time (for example, from .25 to .30). Overdosing is a very real concern, although many fish seem to tolerate rather high levels of copper - sometimes almost double the target dose - for short periods of time with little sign of distress. In the case of an accidental massive overdose, in which the fish appear to be in great stress immediately after copper has been added, partial water changes and the addition of activated carbon to the filter system will help reduce copper levels.

After treatment has been completed, copper can be removed from the system, although complete removal is difficult to achieve - especially if calcareous gravels (including the popular crushed corals or aragonites) or decorations have been used. A significant amount of copper can be stored up in these substances, and slowly leached back into the system as copper levels in the water are lowered. Frequent partial water changes and the addition of activated carbon or certain commercial ion exchange resins will slowly remove copper from the system, but it will probably take a month or more to extract the bulk of the copper. Some aquarists and dealers prefer to keep a fish-only tank permanently coppered, and I have seen fish that have been kept in properly coppered tanks for as long as a year that do not appear to be any worse for wear.

I believe it is the hope of most aquarists that copper therapy might someday become a thing of the past, as new treatments might appear that are safe, effective and easy to use (and as long as I'm dreaming, let's make it "safe for use with invertebrates" as well). But until that day, when I see a saltwater fish start to develop those telltale little white spots, I'm heading for that bottle of copper, the "sure cure" for saltwater ich.


This article originally appeared in
Marine Fish Monthly Magazine

Copyright © 1999 James M. Kostich
All rights reserved.