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To Quarantine or Not To Quarantine?
That’s a Good Question! 

By Bob Goemans


Let’s begin by being very honest – how many reading this article really quarantine their new arrivals?  Probably very few, and that’s quite sad in some ways- but understandable, as many marine hobbyists are not fully aware of the pitfalls their fish incur from the time of capture.  Nor do they understand the association between parasites and their host, whether in the wild or in closed systems (a.k.a., aquariums).

Fish can live in the wild with various parasites and continue to function normally and look healthy.  In fact, many parasites have a special relationship with their host and are simply very happy maintaining a small population of their species without damaging the host.  Simply put, the environment, i.e., salinity, temperature, nutrition, and/or stress level, is satisfactory for both host and parasite to remain healthy and continue their ‘balanced’ relationship.

But it all ends there once the fish is captured, as the balance swings in favor of the parasite!  Once captured, the “fight or flight” response comes into play where all built-in survival strategies are routed to escaping.  The fish then shuts down all non-essential processes such as digestion and the immune system for immediate use of energy for the purpose of escape.  And no fish, no matter how well cared for from time of capture to arrival at your doorstep are as good as they were in the wild.  They are stressed, usually starved, and have been held captive in many different and questionable water conditions of which none come near the pristine quality of their natural surroundings.  So, no matter how good the fish looks, it really isn’t a happy fish!

In addition, the approximate ten days to two week relocation process from the wild to your aquarium is just about what parasites need to take advantage of this “window of opportunity” to increase their numbers.  Furthermore, wounds incurred from collection and/or unsuitable tankmates during relocation are another problem, as bacterial infections often begin in this time period.

Even if fish arrive looking like it is in excellent health, it’s not, and there’s no doubt that the conditions in your aquarium are not going to be what they were in the wild.  Without a doubt, the new arrival will have a smaller world, different mates, different foodstuffs, and reduced water quality to name just a few.  And, past stress levels have given any existing parasites the favorable conditions to begin expansion of their numbers.  The result could be a very good chance of a disease outbreak looking for a place to happen, and that would probably be in your aquarium!

Therefore, excessively politically correct aquarists always say to quarantine all fish before placing them in your aquarium.  In my opinion that’s something like saying “don’t get out of bed in the morning because you may have an auto accident on the way to work.”  That’s just not the way it is in the real world!  The real question to ask when it comes to the value of quarantining new specimens is “Does quarantining increase chances of success?” In my opinion it most certainly does, especially if quarantine facilities are not available at the shop where the specimen is being purchased.  And if so, then there’s no telling what disease, parasite, or unwanted organisms could finally show up in your aquarium if the new addition is not quarantined.

Small quarantine tanks, such as this 10 gallon tank with all the fixings so to speak, are often available through better local shops for less than 100 dollars!  Photo By Bob Goemans

Now, that may sound like I’m being excessively politically correct. However, I’m not saying it is a "must" procedure or that it’s my only stance on the subject.  Other considerations need be looked at, such as your level of disease/treatment knowledge, time and space to accomplish quarantining, and the source from which the specimen is coming from.  Furthermore, it should also be said that quarantining does not guarantee something unwanted won’t slip by and get into the main system.  Nevertheless, it does ‘greatly’ reduce that possibility!  And the bigger and more complex your aquarium, the more you have to lose if you do not quarantine the new specimen.  And as for those that say only healthy fish are purchased, therefore there’s no need for quarantining, I say how can you be sure it’s not a carrier of an internal parasite?  And do you realize that there are far different cycle timeframes for internal and external parasites to either be seen or have a negative effect on its host?  Therefore, even if the fish looks healthy, the “Dump and Pray” method is quite perilous.

Even though the quarantine tank is just that, a small environment that can house a new fish in somewhat comfortable surroundings while its owner makes sure it’s free of any maladies, it can also be easily turned into a treatment tank/hospital tank.  And if it goes that road, the most common external parasites are Cryptocaryon or Amyloodinium, where the usage of copper is by far the most useful treatment regiment.  By the way, there are two different types of copper treatments on the market— Ionic and Chelated, and it’s a good idea to understand the difference between them.

Ionic Copper, i.e., copper sulfate, is generally referred to as free ionic copper.  It does not stay in solution very long since it quickly precipitates, mainly as copper carbonate.  In fact, in an aquarium that contains a calcium carbonate substrate, about 50% of the copper in solution will be absorbed by the carbonate material within the first two hours.  Another 20% is absorbed over the next twenty-two hours.  Therefore, 75% of the initial copper treatment solution is generally unavailable at the end of the first day of treatment (Cardeilhac & Whitaker, 1988).  Hence careful and frequent attention must be given to the therapeutic level of ionic copper since it is constantly depositing or bonding itself to substrate, rock, dead coral, etc.  Dosage rate for most fish are .15 to .20 ppm.

Chelated copper medications are also available and stop or slow copper from precipitating out of solution.  Their copper is bonded with various compounds that solve the problem of having to closely monitor its level and apply additional dosages.  Depending upon the brand used, dosage level will either slightly or greatly exceed .2 ppm.  Nevertheless, the dosage rate with a chelated product is tied to the volume of water in the tank to be treated, and if that volume is misjudged, the treatment can either be ineffective or dangerous to the animals being treated.  And only a test kit made by the company selling the chelated copper should be used to obtain accurate readings.

From the above descriptions, it may appear that chelated copper is easier to use, however, I prefer ionic copper since it can easily be monitored with any brand test kits and a precise dosage level maintained, even though there’s on-going attention and additional dosages.  Nevertheless, whatever type copper is used there are some precautions as its necessary to remove chemical filtering media prior to using it, as it would remove the medication.  Copper will also disrupt biological filtration, therefore its necessary to keep a close watch for an ammonia spike.  Furthermore, long-term unnecessary copper treatments suppress immune systems, making fish more susceptible to other pathogens which is also a good argument against using a chelated product as treatment levels can vary.  Also, keep in mind some Angelfishes, Blennies, Butterflyfishes, Cardinalfishes, Dragonets, and Wrasses exhibit sensitivity to copper.  And since copper increases the animal’s mucus covering, dragonets may suffocate since they normally have a heavy coating of mucus. Thank goodness Cryptocaryon or Amyloodinium rarely affects them.

Keep in mind that copper treatments are ineffective when it comes to external parasitic worms, therefore products containing formalin are quite useful, and there are many commercial formalin-based products on the market.  And their dosing instructions must be carefully adhered to.  Yet bear in mind the effect ammonia has on this product, as it reduces its effectiveness, therefore lowering its impact on the organism to be treated.  Because of that, it’s always wise to keep an exceptionally clean treatment environment by not allowing any detritus and/or uneaten foods to remain.  And frequent water changes are also advised, along with maintaining the therapeutic treatment level. 

The treatment for internal parasites is more complex, as they usually do not manifest themselves early enough to be treated in a quarantine situation.  In fact, it’s necessary to identify the parasite, then treat with specific chemicals to target that known parasite.  Yet, it’s still feasible to see the results some internal parasites may have on their host if maintained in a quarantine situation for 30 – 40 days.  If so, then, depending on the problem area and the identification of the parasite, a specific treatment regiment can begin.  As for bacterial infections, the quarantine/hospital tank situation is the ideal area for treating these type problems.  Better to treat it here than in your main show tank.

When it comes to the length of time spent in quarantine or hospital tanks, it should be recognized that treatment is usually only successful at a certain timeframe in the parasite’s life cycle.  And since we cannot accurately judge when one portion of the cycle begins and another ceases, its better to treat for the length of time the entire cycle encompasses.  Those cycle times can sometimes be found on various websites by simply putting the name of the disease into your web search engine and reading the applicable articles.  I should also add that timeframes could be affected by conditions such as temperature and salinity.  Yet, a period of at least 30 days, preferably 40 days in most cases, is reasonable in my opinion.

Furthermore, quarantine is not only a subject matter that concerns fish, as live rock, live foods, and even natural seawater should get some consideration.  As for fishnets, they are the easiest to disinfect and also the easiest way to transmit diseases between aquariums.  For those with more than one aquarium it is wise to sterilize the net after each use or at least have more than one net and use each on the same aquarium.  A little household bleach in a bucket will do a nice job of sterilizing a net.  Simply dip the net and flush it with freshwater.  Don’t leave the net in the bleach water, as most will quickly deteriorate.  As for live rock, first cycling it in a separate container such as a plastic garbage can will easily reduce its nutrient content, and give one an opportunity to further inspect it for any unwanted animals or algae growth.  It doesn’t guarantee a mantis shrimp or unwanted bristle worms or alga spores won’t make it into the main show aquarium, but the chances of that happening are greatly reduced.  Also, associated nutrients from die-off of small animals and plants are left in the cycling container.

There are also those that feed their marine fish live foods, e.g., goldfish, mollies, guppies, and even small live shrimp.  What I’ve seen of this live food in some aquarium shops is that it’s health and nutritional value is highly questionable.  What better place could they be placed than in a small ‘quarantine’ freshwater or marine aquarium where they can be fattened up and made healthier before being used as live food.

As for freshly collected seawater, it should be used within twelve hours of collecting.  If that’s not possible then other precautions need be taken as seawater can quickly become toxic due to the quick die-off of its plankton.  Keep in mind that freshly collected seawater may look perfectly clear, yet it actually teems with microscopic organisms.  These tiny organisms, animals and plant wanderers commonly called ‘plankton,’ will die-off when their food supply, usually each other, is consumed.  The result can be an ammonia-laden soup.  If the freshly collected seawater can not be used quickly it can be stored in sealed plastic or glass containers in a dark area for up to two weeks.  Darkness simply prevents unwanted algae growths.  Prior to its use the die-off on the bottom of the container should be removed and the water aerated for 24 hours.  Try to collect away from inshore areas where sewage, fertilizer, insecticides, heavy metals and other pollutants tend to collect.

As for seawater storage, a long-term reader suggests adding one bottle cap full of regular household bleach to fifty gallons of freshly collected seawater and then aerating for two days.  Then allowing it to settle for a day, then vacuuming the sediment from the bottom of the container.  Then aerating again for one day and/or until no smell of bleach remains, then storing/using as needed.

In all honesty, it’s not unrealistic to expect good results in treating the show aquarium if a disease breaks out in a ‘fish-only’ system.  Nevertheless, practicing good quarantining procedures initially, in my opinion, is the way to go.  And that quarantine tank can be as small as a 10 gallon aquarium having an external biological filtration system, strong aeration, and sufficient decoration.  Simple decorations such as artificial rock will help make the new fish feel somewhat at home while in the transition mode.  Of course, size of this aquarium depends upon the size of the animals to be quarantined.  And if a sandbed is desired, use a non-calcareous medium incase copper treatments become necessary. Additionally, the ‘quality’ of the water in the quarantine tank should be equal to that in the show aquarium, i.e., same pH, salinity, and with no ammonia and nitrite.  While in this temporary home should a serious parasitic or bacterial infection occur, the tank could be transformed into a hospital tank.

Where fish are concerned, the choices are clear: dump and pray; quarantine; or, have the local dealer hold the specimen for at least ten days while the animal has a chance to regain some of its stability.  For those of you that want to “save” the fish from the local shop’s tanks, if they are that bad, the three choices are now reduced to one – quarantining!  Those purchasing through mail order have only the first two choices.

Early detection, accurate identification, and correct treatment regiment.  Quarantining is easier said than done, but well worth the effort!  Sadly, most hobbyists continue to use the "Dump and Pray" method. Let's hope that more hobbyists embrace a quarantine protocol in their husbandry routine!

quarantining b/f's and mandarin?   6/8/11
Good morning,
I will be receiving 3 B/F's and a Mandarin Fish mail-order later this week. I have a 30g quarantine tank ready to go but have a couple of questions.
Would it be best to do a PH-adjusted, freshwater dip w/Methylene Blue, on the Mandarin and place him in my established 125g FOWLER tank?
<Yes; this is what I would do; not quarantine this family (Callionymidae) and a few other fish groups, unless there was something apparently "wrong" with them>
After reading most of the FAQ's on these fish, I realize they are not as susceptible to Ich but I am quite paranoid about its (Ich's) re-introduction into my tank as I have battled it on and off for two years (luckily with me winning or more likely in a stalemate with the enemy!) with no loss of fish.
<Mmm, well... up to you>
On to the B/F's! I'm getting a Tear-Drop, Pakistan and Black-Backed. I realize these fish are quite sensitive and will most likely start eating prepared foods and re-build their resistance once placed in the main tank, but would a week or so in quarantine then a freshwater dip w/Methylene Blue or Formalin (safe for B/F's ?)
<Toxic, but if they're in "good shape", likely worth using>
be better for the fish than acclimating them, freshwater dipping them and immediately placing them in the main tank?
<I would likely quarantine these, given your system (the 30)>
I've read about every FAQ's on B/F's and added to them with some of my questions in the past but I am on the fence here on whether to quarantine or not.
<Me too/I as well>
Even though I have run my tank fallow for several 8-week periods over the last two years I know I still have some entrenched Ich. The last time I added 4-week quarantined B/F's I had an outbreak but decided to treat with Selcon soaked Spectrum flakes and Spectrum Thera-A pellets. The fish kept the cleaner shrimps very busy, but all came through and continue to thrive.
My point is, quarantining or not, with my particular tank, probably means a small outbreak of Ich once new fish are added.
Lastly, even though the HOT refugiums are small, about 3-4 gallons, would you recommend one for pod growth for the Mandarin or am I wasting my money?
<Are worthwhile. Even what appear to be small volumes of "live" sand, other substrates, macro-algae, a very considerable amount of life is produced>
Thanks in advance for all your insight and wisdom. I spend most evenings perusing your excellent site and wish you all lived closer so I could buy you a beer or two!
<Oooh! Let's hope we meet! Bob Fenner>

Anthias and Wrasse harems   3/19/11
<Hello Dustin!>
I currently have 4 Bartlett's Anthias in a 29 gallon QT tank.
<Mmm, need more room by this by far... Will be both psychologically and socially, let's combine the two terms, psychosocially too cramped in a very short while>
They have been
there for a week and all seem to still be females. For the first couple days all of them were eating and swimming around. Now one is hiding behind the powerhead
<Oh, already. See, I did state "in a very short while">
in the tank and not eating and another has a pretty beaten up tail fin,
but is still swimming around and eating. My assumption here is that there is some jostling for dominance going on,
<In part, yes>
but I don't want it to be at the expense of a couple of them dying.
<Which they will if not moved>
What can be done to help this situation?
Do they need to be partitioned or separated in some way?
<Not in this volume, no>
The Anthias are going into my 210 gallon upon completion in QT.
<Anthiines are one of my "generally don't quarantine" groups/families of fishes... They suffer too much from the delay, compared with simple dip/bathing and expedited placement in main/displays. Is this clear to you?
Like most Gobioids, Blennioids... much more of the time these fishes "die mysteriously", jump out, starve, beat each other up... I'd place them in the larger system, stat.!>
This carries over into the harem of Flame Wrasses I just purchased them today and put them into a different 29 gallon QT tank.
<These two I'd dip (pH adjusted freshwater... detailed on WWM:
and the linked files above)>
The harem consists of 1 male and 3 females. I want to make sure I don't run into the same problems
I am currently having with the Anthias.
<Similar, yes... Move these Jordan's Cirrhilabrus>
The only decor in either tank is a few PVC pipes, a heater, a powerhead, and an air stone.
Thank you in advance for your assistance!!
<Certainly welcome. Bob Fenner>
Re: Anthias and Wrasse harems– 03/19/11
Thank you for your help. I figured you would say to move them over, I just needed you to push me over the edge to do it. I really don't like not quarantining anything.
<Ahh; is at least a two-sided saber>
I think going forward I will have a 75 gallon quarantine tank when introducing groups/harems so that I can
quarantine (not for the 210, but when I upgrade). Would this be sufficient or should I not quarantine in any size tank really?
<... not certain species...>
Thanks again,
<Another welcome. BobF>

To quarantine or not to quarantine... that is my question   4/16/07
Aloha boys and girls. My name is Alex (and I'm an addict...?)
<Sounds like you're ready for our 13 step pet-fish program... the thirteenth is where you turn around and go back to number one!>
and I would just like to thank you all for giving your time to this wonderful resource.  I owe much of my success in this hobby (just passed the 3 year mark with a beautiful sps dominated tank) to all of you for answering the questions posed by others and posting them for us all to read.
<Ahh, tremendously pleasurable to realize>
I myself am a long time reader but this is my first time writing. My question is this. I've just ordered a Blue Tang (Paracanthurus hepatus) from Live Aquaria and was wondering if what I read was true? Like I said I'm an avid reader (daily) of your wonderful site and I remembered reading a while back an article regarding acclimation on this particular fish. In your article Paracanthurus hepatus, the Pacific Blue Tang of Many Names you say not to quarantine this fish.
<This is my standard assertion re this species, several others... But some of the rest of the Crew here are more "strict" concerning carte blanche acclimation of marine (et al.!) livestock>
Under the Introduction/Acclimation section of this article you state to just do a PH adjusted freshwater dip and than add the fish to the main display. Is this true?
<Yes... unless the specimen/s (including other species in the same shipment) show obvious behavioral and/or parasitic anomaly>
Is this still your opinion?
<Yes... with the above qualification>
I'm a true believer in using a QT having never lost a fish or had any issues and have a 30 gallon up and running for this purpose.
<Good. A good size>
I'm somewhat in agreement that the stress involved in moving the fish from one tank to another may out weigh the benefit of the quarantine but is it worth the risk of possibly introducing ich or some other pathogen to my well established tank?
   Thank you for your time (YOU GUYS ROCK),
            Alex Mattern
<Mmm, well... where/when in doubt, I default to the more conservative end of actions, considerations... Do quarantine the new Tang if you would like (along with FW dip/bath) enroute to the QT... For myself, having handled many specimens in commercial settings, much more likely/often the dip/bath alone is more efficacious. Bob Fenner>

On Quarantine on WWM

Related Articles: Acclimation, Quarantine ppt., pt.s 1, 2, 3, 4, 5, 6, 7 by Bob Fenner Quarantine, Quarantine of Marine Fishes, Quarantine of Corals and Invertebrates, Biological CyclingMarine Ich: Fighting The War On Two Fronts, Cryptocaryoniasis, Parasitic Disease

Related FAQs: Best Quarantine FAQs, Quarantine 1, Quarantine 2Quarantine 3Quarantine 4, Quarantine 5, Quarantine 6Quarantine 7, Quarantine 8, Quarantine 9, Quarantine 10, Quarantine 11, Quarantine 12, Quarantining Invertebrates, Quarantine Tanks & FAQs, Quarantine Filtration & FAQs, Quarantine Maintenance & FAQs, Quarantine Feeding & FAQs, Acclimation 1, Acclimating Invertebrates, Acclimation of Livestock in the BusinessTreatment TanksAmmonia, Nitrites, Nitrates


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