Write-Up Wednesday: Tank Transfer Method For Disease Control

Two of the most common diseases saltwater fish can get in captivity – marine ich (Cryptocaryon irritans) and marine velvet (Amyloodinium ocellatum) – have suggested a treatment method called the “tank transfer method”.

To understand the tank transfer method, you’ll first need to have a basic understanding of these diseases’ physiology.

Both diseases infect fish via a parasite that spends parts of it’s lifecycle on the fish and part of it’s lifecycle off the fish. The off-fish lifecycle is important for two reasons:

1) It causes experienced hobbyists to mistakenly believe their fish has been cured of the diseases. This false belief occurs because symptoms either disappear completely, or are reduced. In case of these two diseases, the white spots on the fish are either gone or noticeably reduced. Note that the fish certainly isn’t cured and don’t be fooled into thinking so.

2) While the disease is off the fish, it will spend between 2-28 days attaching to a solid surface, encysting and reproducing. Once done reproducing, it enters a free swimming stage and looks for a new host.

The idea behind the tank transfer method is that by repeatedly removing the fish from the tank where the disease is reproducing, and placing it in a new tank free of the disease, then the cysts can be destroyed and never have a chance to reinfect the fish.

Note that the tank transfer method involves at least two properly setup quarantine tanks. Part of the tank transfer method involves sterilizing the tank which cannot be done with a display tank. (I really don’t think you want to nuke your display tank…)

While the tank transfer method can work, it has some drawbacks that keep me from using it:

1) It’s labor intensive. Every other day, the fish must be caught and placed into a new quarantine tank and the old tank properly sterilized. Also, the new tank’s parameters must be matched to the existing tank and a stable colony of nitrifying bacteria has to be present to prevent ammonia spikes which can kill the fish.

2) The fish must be handled frequently. Netting a fish can cause secondary infections, especially when the fish is stressed like when it has marine velvet or marine ich. Even if the fish is caught with a transfer container such as a fish trap, then the frequent movement of the fish to a new tank can stress the fish, hampering its recovery.

I do not use the tank transfer method partly for the reasons above and mostly because I have had a lot of success with using a proper copper treatment regime, even with sensitive fish. If you’re looking for a no-medication approach to treating marine ich or marine velvet and you’re willing to put in the work to do it properly, including educating yourself on proper fish quarantine procedures, the tank transfer method is worth considering.

Finally, note that the tank transfer method is effective for marine ich and marine velvet only.

(If you’re looking for the facts on fish diseases and treatment, supported with actual scientific studies, my No-Nonsense Guide to Marine Fish Diseases, Treatments and Quarantine is on sale until 11pm on May 6th)

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Comments for this article (9)

  • Shawn says:


    What kind of preventative medications do you recommend for quarantining a new fish? I quarantine mine before they join my tank but am unsure of what to treat them with. Should I use Cupramine and/or Paraguard?


  • Derrick says:

    I Introduced ich into my DT by way of a non-QT’d fish. Bought a QT tank and ran hypo-salinity (bare-bottom) for 5 weeks, and then began raising salinity over the next 4 weeks. The DT had no livestock for a total of 9 weeks. All fish are back in the DT and I’ve had no ich sightings in 4 months. I’ve introduced be fish into the DT since then but not without QT/hypo(if necessary).

  • Michael says:

    Hey, I too would like to know what preventative meds. should/could be used to best effect in an initial quarantine. I purchased your books through the sale but have not gotten to the FD&Q book yet so if it covered in there than I’m unaware. Thanks 🙂

  • Tom says:


    I’m so glad that you mention this method of quarantine even though you choose to not use it yourself. I’ve been in the hobby over 35 years and have used this method countless time over the last 20+ years. It definitely works if done correctly. However, unlike you, I have actually found that this is a great method for the more sensitive/delicate fish. I don’t use copper/chemicals of any kind at all, as I think it does negatively affect the internal organs of fish to some extent, even if it doesn’t kill them. To me, copper/chemical treatment equates to a chemo therapy analogy – enough to kill the disease with out quite killing the fish. However, the fish is still negatively affected in the process, at least in my opinion, and the sensitive fish even more so. I think the negative affects of the transfer method on sensitive fish are less than copper if done correctly with lots of care given to the method of capture/transfer of the fish, as well as having parallel water parameters in all new tanks to be transfered into. Also, if you use this method, I’ve found it’s much more advantageous to use rubbermaid totes as quarantine tanks rather than small glass aquariums. It’s much easier to clean/sterilize them after each transfer. I just rinse them out with scalding water and then dry them for the next use. Labor intensive indeed, but 100% effective based on my experience. Taking this effort and time up front is definitely worth the peace of mind you get about your display tanks afterwards. Thanks for advocating for the various types of “effective” quarantine methods. I, like you, once learned the hard way and will never go back. 🙂

  • Chris says:

    I agree with Tom above about chemical treatments and prefer to use them only when absolutely necessary.

    There are a few inaccuracies/misconceptions with the article:

    1. Tank Transfer Method (TTM) only works for Cryptocaryon, not Amyloodinium. Fish should be observed for 1-2 weeks post-TTM to ensure they are not infected with Amyloodinium or Brooklynella. This time period can be used to treat for flukes with praziquantel.

    2. Transfers are made every three days, not every day. 72 hours is the minimum time frame for tomont excystment, so this ensures there are no free-living theronts that might be transferred to the clean tank. Transfers are made on day 4, 7, 10 and 13 (Day 1 being the first transfer into a clean tank). Transfers can also be done every two days, with 5 total transfers, but that’s a lot of extra work for little added benefit. The three day period also ensures enough time for equipment to fully dry before being used again.

    3. Ammonia is typically not a problem with TTM, unless you are treating a large number of fish at a time. For a single fish, ammonia can be dealt with using Prime (or similar ammonia detoxifier) at the end of the second day. You could also use seeded media from your sump to establish a biofilter (assuming your DT is parasite-free, of course!) Likewise, ceramic media in a HOB filter combined with a small amount of bacteria-in-a-bottle (like Bio-spira) can also work.

    TTM is preferable to chemical treatments because it targets the most predictable phase of Cryptocaryon’s life cycle – the protomont. By eliminating the organisms ability to form tomonts, you remove the infective stage entirely. Chemical treatments like copper only affect the free-living (infective) theronts. Tomont excystment can vary greatly — anywhere from 3 to 72 days. So, you could potentially treat for 30 days and still not eliminate the organism completely.

    Finally, chloroquine phosphate (CP) is the preferred treatment for Amyloodinium, and it is better tolerated by most fish than copper. A dose of 10mg/L for 10 days is recommended. It can be used for Cryptocaryon as well, but the treatment challenges are the same as with copper as noted above.

  • Riaan says:

    Thank you for highlighting this method. I’ve been using it for at least the last 4 years.

    It is very difficult to treat for Cryptocaryon irritans (CI) in a tank, be it holding or display. My logic says that if it is difficult to treat a fish in an infected area, why not take the infected area away from the fish.

    I use plastic buckets or tubs. I got a couple available, 2 per size, from 30L to 80L. I transfer the fish every second day. I do not use a net at all! I believe you cause more damage to sensitive fish scales and fins with a net. I use a very small glass fish tank, 20cm by 20cm by 10cm wide. Put it in sideways and use a piece of eggcrate to herd the fish into the small tank, Turn it upright, drain most of the water and move the fish over to the new bucket. After all, the stage we are at the CI is dropping off the fish trying to encyst on the bottom. If I do scoop up a few, does not matter, they will encyst in the new tub and only got 2 days before that tub gets nuked in the sun.

    The old dirty tub gets filled with tap water overnight. Drained the next morning and placed against a wall in the sun for 2 days.

    All equipment is also double. I use a small 200L/h pump placed pointing up for circulation. And a 50W heater. Hang the pump and heater also up against the wall for 2 days in the sun to properly dry out.

    Further, I use those hide-aways for reptiles, Those that look like rock. They are solid and clean easily. Again, got 2 of them, one in the tub, the other in the sun.

    On each transfer, i drain the top 50% water from the old tub into the new tub. This removes the requirement to drip acclimatize the fish. I use an inline 5 micron filter when I siphon the water over. The minimum size of CI when hatching is 20 micron. I open the filter up after use and put it in the sun to dry out.

    The new 50% water gets added slowly using a plastic 30L container with a tap placed above the tank. The tap is opened slightly so that the refill takes about an hour. PH, salinity and temperature issues are sorted doing this.

    After the 5 transfers the fish do go into the holding tank for observation for 5 weeks.

    It takes me about 20 minutes to do each transfer on the 40L tubs. It is really not that big a problem. in total, less than 2 hours when you total all the transfers together. Compare this time cost against the value of all the fish in your display.

  • paul says:

    Do you people have access to polyp lab medic for ick, its simple ,it works (in a reef) and Ive used it twice in two differant tanks in last two years with no losses of any life whether fish, invert, coral or bacteria, and importantly it doesnt stress fish, I cant believe I dont hear it mentioned more often. I treat my fish in the reef its very easy.

  • Riaan, Chris…thanks for the comments. I’ll do some researching and see if I need to amend the write-up.

  • Shelley says:

    As others have stated marine velvet is not treated by TTM, tank transfer method. I hope you will update your your writing on this subject. TTM works for marine icy.


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