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Effective Quarantining: Reducing The Risk of Disease


Effective Quarantining: Reducing The Risk of Disease

To 'quarantine? simply means to temporarily house a new fish in a separate tank before introducing it to the main tank. This helps prevent potentially lethal diseases being transmitted to established fish collections and consequently most professional fishkeepers regard it as essential. However, the success of quarantining varies widely depending on the approach of the fishkeeper. This article suggests some ways in which to get the most benefit out of quarantine.

It is 100% certain that every new fish is carrying at least one ?bug?, even if it looks perfectly healthy. Diseases are especially widespread at pet stores due to the tanks being linked on the same water system; pathogens can move round easily and attack already stressed fish. The five most common problems affecting new fish are:

1. Ich

2. Flukes

3. Ammonia burns, either fresh or healing

4. Physical injuries such as scale loss caused by rough handling or overcrowding

5. Severe stress from transportation, overcrowding and poor water quality.

The length of quarantine depends on the individual fish and its circumstances but should not last less than three weeks. A fish which does not display any signs of disease and is eating and swimming well could be moved once treatment sets One and Two (see below) are completed, which takes about 3 weeks. Incidentally, one reason for maintaining a high temperature in a quarantine tank (see below) is to ?bring out? many temperature-responsive diseases such as ich, consequently speeding up quarantine time. Below 65F some diseases can take several weeks to emerge, so if a heater is not used then quarantine must be kept up for longer.

The following equipment is recommended for a quarantine set-up (this also works for a hospital tank):

? Tank which allows at least 10 gallons per goldfish (less for other fish)

? Quiet location, where the fish will not get disturbed much

? Pre-cycled filter (use media from an established filter for ?instant cycling?)

? Heater set to 78F / 26C (heater guard optional)

? Thermometer

? Additional aeration if the filter does not move the surface much.

? Light layer of substrate (this gives goldfish something to keep them occupied)

? Few plants / ornaments to provide hiding places and make the fish feel safe (no live plants except Java Fern however, which is salt-resistant)

? Small mirror taped to one side of the glass (if a quarantined fish is alone)

? Separate set of tank maintenance equipment e.g. bucket and gravel-siphon, OR a bleach solution with which to sterilize equipment between tanks.

A quarantine tank should be maintained more intensively than a main tank. Daily small water changes (up to 30%) with gravel cleans are recommended even though the tank is cycled. This is because very clean water greatly reduces stress, boosts the fish?s immune system and naturally suppresses some diseases such as Trichodina and Epistylis. It is best to test the water of a quarantine tank daily, as poor water quality in quarantine is likely to affect new fish very badly. It is also important to observe the fish closely during quarantine ? including appetite and activity levels - as the whole idea is to check for any developing diseases and problems.

As for feeding, when Treatment Set One is not being applied, a varied and highly nutritious diet (krill is especially good) is recommended to boost the fish and give it a good start. Fish often do not get fed for several days after they leave the breeder and can arrive very hungry. Feed as much as the fish will accept twice a day for up to three minutes at a time.

The lighting should be kept fairly subdued (actually I prefer to keep the quarantine tank just in natural light) to reduce stress. The fish should also be given at least 8 hours darkness each night as this significantly helps reduce stress and disease and allows the fish plenty of rest and recuperation.

Turning to disease-control, unfortunately fish can frequently carry a disease without ever showing a single sign of it. Even if plastered head to tail in bugs, they can build up a natural immunity and remain undisturbed. As such, even four weeks of quarantine can be completely useless if the fish itself never shows a sign of the disease and then introduces it to the fish in the main tank, which of course are susceptible to it, having not built up immunity. There is nothing more frustrating than the whole collection breaking out in ich two days after introducing a lengthily quarantined and healthy-looking fish!

Therefore it is better to actively treat the fish during quarantine time and pre-empt any lurking diseases, rather than to simply wait and see if it develops anything nasty. In other words, you actively quarantine rather than passively quarantine. What follows below are recommended treatment ?sets? to apply during quarantine which systematically eliminate as many potential ailments as possible before the fish goes into the main tank. Each set tackles a specific collection of diseases using a particular treatment method and takes a given number of days to complete, although of course treatment times may vary if the fish actually develops a disease.

However, the key word here is ?actively? treat, not ?aggressively? treat. The idea is only to gently banish potential problems, not to subject the new fish to a barrage of stressful chemicals and procedures. The treatment sets therefore reflect this philosophy of gentleness: salt is perfectly safe for fish and the bio-cycle (Set One), as are praziquantel (Set Two) and lufenuron (Set Three). Medicated foods such as Medigold or Romet B (Set One) are not only gentle on the fish but are also generally tasty and highly nutritious.

Please note that the sets do not deal with every single fish disease; Oodinium (Velvet), for example, is not covered. I have deliberately left some out, either because the disease is relatively rare and therefore there is little point in taking additional specific precautions against it, or because the treatment for it is so harsh ? such as copper or formalin - that the fish has to actually have the disease first to justify using it, at which point the quarantine tank becomes a hospital tank and therefore has no place in this article.

The order in which to apply the sets depends on the individual fish and the conditions it came from. For example, if the dealer?s tanks were rife with ich, then use Set One - which treats ich - first. However, if a new fish shows signs of a lice infestation then use Set Three first and then go to Sets One and Two later on. It does not overly matter what order they are used in, providing the sets are all worked through at some point. However, if the fish shows no sign at all of disease when you purchase it (which is to be hoped for!) I would recommend using the treatment sets in the order they are listed. This is because Set One tackles the widest range of possible ailments ? containing four of the five most common problems found in new fish - and therefore you stand a good chance of zapping plenty of things before they get going. While Set Two is absolutely essential ? because One will not treat flukes and flukes are among the most common and deadly parasites - it treats a much narrower range of problems and therefore is less immediately beneficial (unless of course you think your fish is suffering significantly from flukes, in which case use Two first).

Also, you can of course stop one set and start another if the fish develops a disease which the current set will not treat. For example, if you are in the middle of One and the fish breaks out in anchor worms, clear the salt from the tank with two or three large water changes and switch to Three, or to a different treatment type altogether if required. The usual precautions when medicating apply: do not mix any medications and always clear one lot by water changes or using activated carbon in the filter before using another (and don?t forget to remove the carbon before adding a new medication). Aerate the tank well throughout the process and maintain water quality.

Please note that the below treatments all pre-suppose a tank which is consistently maintained at perfect water quality, with all water changes being carefully temperature and pH-matched each time. It also pre-supposes correct acclimation of the fish to the quarantine tank (see the Tip of the Month forum for advice on how to properly acclimate a fish).

Treatment Set One (bacteria and ciliated protozoan parasites)

Requirements for fourteen days:

? Tank salted to 0.3%

? Consistent temperature of 78F

? Medicated food such as Medigold or Romet B, if available*


? Chilodonella

? Costia

? Columnaris (body fungus, cottonmouth)

? Epistylis

? Ich (whitespot)

? Finrot

? Underlying or broken ulcers (body sores)

? Saprolegnia (fungus)*

? Internal and external pathogenic bacteria

? Carp Pox

? Trichodina*

Also helps to treat:

? Physical injuries inc. scale loss, abrasions, white-eye caused by corneal damage, torn fins/tail and osmoregulation problems caused by injuries

? Stress following transportation / handling

? Previous ammonia burns or nitrite poisoning

Salt the tank to 0.3% following the usual method (for instructions on salting see the Disease Treatment forum) and feed medicated food as directed on the container. Keep this routine up for 14 days, remembering to replace the salt whenever you do water changes.

*There are some strains of Trichodina which are resistant to salt at 0.3%, but will respond to 0.6%. If you suspect the fish has Trich, and if it is not weak or very tiny, gradually increase the tank salinity to 0.6% using the same method as before and hold it there for 5 days. If you cannot increase the salinity, use another treatment such as potassium permanganate or Interpet Anti Parasite Remedy.

*True fungus does not respond very well to this treatment, though mild cases can be cured or prevented with salt. If a fungus infection worsens use a proprietary fungus remedy.

*Medicated food is not available in the UK. If you suspect the fish has a bacterial infection, remove the salt and use a water-based treatment such as Interpet Anti Internal Bacteria or Interpet Anti Fungus and Finrot or Waterlife Myxazin (or if the infection is severe consult a vet). If you do not think is has a bacterial problem however, skip this stage as salt is a natural antibacterial agent and will have knocked off most bacterial pathogens already. Feed nutritious food during this set instead.

Treatment Set Two (flukes and internal worms)

Requirements over seven days:

? Tank dosed with praziquantel (Prazi-Pro, Fluke Tabs or Droncit*)

? Consistent temperature of 78F

? Varied nutritious diet


? Flukes

? Intestinal worms such as tapeworms and red worms

*Note: None of these are available in the UK except from a vet, or use Waterlife Sterazin or TetraMedica Contraspot.

Apply the praziquantel to the tank and leave for three days. Do a large water change and re-apply for another three days. Then do water changes to get rid of the praziquantel (which is deactivated after three days anyway). If you think the fish is badly infected with flukes this treatment can be repeated again. Alternatively use the Sterazin or Contraspot as directed on the packet. Use activated carbon to clear the last traces before starting set Three.

Treatment Set Three (crustacean parasites)

Requirements over 5 days

? Dimilin, Program or Larvadex (lufenuron)*

? Consistent temperature of at least 70F

? Varied nutritious diet


? Argulus (Fish lice)

? Lernea Elegans (Anchor Worms)

? Ergasilus (Gill Maggots)

Crush the Dimilin or Program tablet, mix the powder well with old tank water (shaking it up in a jar is best) and apply to the tank. Leave for five days and do a water change. Use activated carbon to remove last traces. If needed, this treatment can be repeated. The dosage for Dimilin is 1 gram per 1,000 gallons (it is completely non-toxic to fish or bacteria so an overdose of any size does not matter). The dosage for Program or Larvadex is one quarter tablet for a 20 gallon tank (again an overdose, but it does not matter). Alternatively, dose the tank with Interpet Anti-Crustacean Parasite as directed on the instructions.

*None of these are available in the UK, except from a vet. Instead, use Interpet Anti Crustacean Parasite. However, this is med is very aggressive and destroys the filter bacteria, so skip this step unless the fish actually has a crustacean infection, in which case it is justified. I would keep the fish in quarantine (re-salt the tank to 0.3%) for a further week after this treatment to be sure no further outbreaks occur and to give it a chance to recuperate.

Finally, once quarantine is over adjust the tank temperature to match that in the main tank and move the fish over. When you move it, acclimate the fish to the main tank just as carefully as you did in the quarantine tank. It will be used to cleaner water than you probably have in the main tank (less nitrates for example, because of the daily small changes), and could get shocked by an abrupt change in water chemistry. Observe it carefully for the next few days to ensure it has settled in properly.


Dr Erik L. Johnson and Richard E. Hess, Fancy Goldfish: A Complete Guide To Care and Collecting, reprinted 2004, Weatherhill, New York.

David E. Boruchovitz, The Simple Guide to Freshwater Aquariums, 2001, T.F.H. Publications Inc., New Jersey.

Dr Chris Andrews, Adrian Excell and Dr Neville Carrington, The Interpet Manual of Fish Health, 2002, Interpet Ltd., Dorking, United Kingdom.

Dieter Untergasser, Handbook of Fish Diseases, 1989, T.F.H. Publications Inc., New Jersey.

Dr Johnson, Articles Section, www.KoiVet.com.

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