Treating Marine Ich

The Low Down on the White and Round

If you stay within the hobby long enough, at some point you will encounter any number of aquatic diseases which plague our fish. Marine Ich is one of the more common ailments witnessed within the aquarium trade. Sometimes referred to as “white spot disease”, marine ich can be identified though the appearance of small white dots which can be found on the fish's skin, fins and gills. The size of the of the dots can range from 0.5 - 2.0 mm. As the disease progresses, more spots may appear throughout the fish’s body, eyes become cloudy, the fish may refuse to eat becoming lethargic, and could ultimately lead to death. We are going to discuss exactly what causes this white spot plague and evaluate treatment options. ​

What Causes Marine Ich?
Before we can discuss treatment options, we must understand the creature which causes ich to occur. Ich is the result of a marine protozoan named Cryptocaryon irritans penetrating into the skin and gills of fish. Protozoans are generally single-celled microscopic organisms. The white spots of C. irritans visible on the skin of fish are only one part of a 4 stage life cycle. Let's review each step.

Trophont Stage - This is the stage of the cycle we visually witness as white spots on the fish’s skin. During this phase of the protozoan’s life cycle, it can spend anywhere from 3 - 7 days feeding on the host fish. The white spot we witness is a cyst surrounding the C. irritans. Once the trophont is mature, it bursts free from cyst and enters the next stage.

Protomont Stage - During this stage, C.irritans is free swimming and looking for a solid location to settle. This could include substrate, rock or even wet objects such as nets (resulting inadvertently to contamination of other tanks). The protomont will crawl around for upwards of 18 hours looking for a suitable location. Once the protomont has selected a area, it will begin to encyst signifying the next stage in the cycle.

Tomont Stage - Once the protomont has become encysted, it is then classified as a tomont. Inside of the tomont, numerous cellular divisions are leading to the generation of new parasites called tomites. This stage typically lasts 3 days; however, the encapsulated tomonts can last for up to 28 days. It is during this period in time that the C.irritans are lying in wait. Many aquarists believe they have outwitted the disease only to have the spots reappear a few weeks later as a result of these dormant cysts. Once the tomites hatch free from their tomont, they enter the final stage of the cycle.

Theront Stage - After the tomites hatch and become free swimming, they are referred to as theronts. Theronts cruise the water looking for a new fish host to begin the cycle again. However, theronts have limited time of 24 hours to infect a new host or else they perish.

Treatment Options
I'm sure you're thinking, thanks for the biology lesson but I really just want to know how to get rid of it! I completely understand and sympathize with the stress that accompanies trying to treat a sick fish. However, I believe that understanding Ich's life cycle is necessary when choosing a reliable treatment method. The following 3 choices are among the most dependable options available for curing fish of marine Ich.

1.) Copper ~ Cu Later Ich!

There are many products on the market which will enable you to safely add copper to the water column while limiting harm to your fish. The copper treatment works by killing the free swimming theront stage of the cycle. Unfortunately, the copper is not effective against the cyst stages of the Trophont & Tomont.

Shortly after acquisition, we had a blue tang develop ich while in quarantine. We relied on Mardel Coppersafe for treatment. Below you can see how the tang recovered over a month period. Following the month treatment period, we removed the copper utilizing water changes and carbon. The tang remained within quarantine for an additional 3 weeks to insure that we did not witness any recurrence of the illness.

If you decided to utilize this method, please read the directions on the bottle of the product you have selected and follow accordingly. Keep in mind that many aquarium inhabitants are intolerant to copper treatments. Scaleless fish such as gobies, mandarin, and pufferfish are extremely sensitive to copper. Many invertebrates will be killed if exposed to the treatment. Therefore, it is important to treat affected fish in a separate quarantine tank.

Drawbacks: Copper treatment is stressful on the fish in which you are trying to treat. During the treatment process, it is not unheard of for fish to loose their appetite. Damage can also be sustained to the fish’s kidneys and liver if guidelines on the bottled treatment are not strictly followed.

2.) Hyposalinity ~ A Little "Hypo Healing"
This methodology involves changing the salinity of the water in order to eradicate the infectious protista. In order to implement this technique, you will need an accurate refractometer to determine your specific gravity. The process involves lowering the specific gravity to 1.009 and leaving the fish within this hyposaline environment for a month.

The hyposalinity treatment method is detrimental towards invertebrates, coral and organisms living within your live rock; therefore, it is highly recommended to utilize this treatment method within a quarantine tank. Begin the quarantine tank with a specific gravity which matches that of the main tank. We assume most tanks are kept around a specific gravity of 1.025. You will need to gradually lower the specific gravity over time to minimize the stress placed on your fish. Over a 5 day period, gradually bring the specific gravity of the tank down to 1.009. This can be achieved by removing small amounts of tank water and replacing it with R/O water. The fish will need to remain in the 1.009 salinity for 4 - 6 weeks. After the treatment period, you can begin to gradually raise the salinity back to 1.025. We recommend raising salinity over a period of 7 days as this process is more stressful to fish then lowering the specific gravity. 

Throughout the entire treatment process, watch out for pH swings! When lowering the salinity, we recommend adding R/O water that is already matched with the pH and temperature currently in the tank. pH swings can be extremely detrimental to your fish. We highly suggest measuring pH twice daily in order to adjust for pH swings. Additionally during the quarantine period, you will need to monitor ammonia, nitrite, & nitrate levels daily. Utilize water changes to bring these levels within safe parameters.

After treatment and the specific gravity has been returned to 1.025, keep the fish within quarantine for an additional 4 weeks to monitor for reinfection. If any dots appear, begin the process again.

Drawbacks: This method requires plenty of methodical thinking. You must gradually raise and lower the salinity over time while examining several parameters. Ammonia, nitrite, nitrate, pH and salinity will need to be carefully monitored throughout this process. During frequent observations should parameter swings be witnessed, immediate action will need to be taken to rectify the issue. Once again this process will place the fish under stress.

3.) Tank Transfer Method ~ Fight or Flight...Why Not Both?
This treatment method “fights” ich through “flight” or specifically moving your fish away from the problem. I highly recommend this option if you are wary of jumping straight for medications & feel intimidated by the hyposalinity treatment.

For this method, you will need two quarantine tanks. Begin the treatment by placing the fish in the first quarantine tank. After 3 full days, transfer the fish into a fully prepared second quarantine tank. The transfer should be conducted at the beginning of the day as the parasites fall off the fish during dark periods (night). After the transfer, the first tank will need to be broken down and have all of its equipment thoroughly disinfected. Following cleaning, the newly sterilized tank will once again be prepared to receive the fish again in three days time.

The premise behind this technique is that as you move the fish from tank to tank, you remove the fish from the protomont, tomont & theront stages of the life cycle. This process will gradually deplete and eliminate the parasite from the aquatic environment. In order to insure that you have eliminated the parasite, you will need to complete this transfer process a total of 4 times. Below is a day by day breakdown of instructions for clarity.

Drawbacks: This process is more expensive in that it requires two sets of quarantine tanks and equipment. It also places the fish under stress as they are transferred from tank to tank. In order to try and minimize the stress, make sure that the salinity and temperature of the two tanks is as close as possible. Additionally, we recommend transferring the fish with a small plastic tupperware container or strainer in order to avoid nets.

In Conclusion
Several species of fish are notorious for contracting marine ich. Tangs in particular are typically referred to as ich magnets. Each treatment option comes with its own array of benefits and drawbacks. When selecting a treatment method, you must evaluate the fish you are trying to cure along with your own personal level comfort with the method. The three methods we described are among the more reliable treatment options.

Unfortunately at some point in this hobby, everyone will probably have to deal with a case of ich or some other illness. This is why quarantining new aquarium acquisitions is so vitally important. If you need further convincing, read our article surrounding the demise of Darwin our discus fish. It is much easier to treat a single fish for ich rather than trying to treat an entire tank. Additionally, it is always a good idea to keep a “fishy first aid” kit on hand just in case any marine disease appears in your nautical menagerie.

Hopefully we've provided you with enough insight to select the treatment method which works best for you. Best of luck to you & your fish friends!

Keep Krill'in!