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)Browse the Store! Questions?