Quarantine and hospital tanks
By: Russ


There are many similarities and also distinct differences in how hospital and quarantine tanks are managed.

While a quarantine tank may very well turn into a hospital tank over the course of a fish’s acclimation, a hospital tank is employed for the purpose of treating fish for illness or other physiological damage.

A quarantine tank is primarily utilized for acclimation of new fishes to the water conditions they can expect to encounter in one’s main tank, or destination tank. Similarly, one observes their fish during their acclimation period for any signs of stress or disease.

In addition, a quarantine tank can be used for both aquatic plants and fish. Although, the quarantine period between fish and plants can very for plants from a matter of a few hours for plants, it can be up to 40 days for fish. I might point out that new fish and plants should not be quarantined together in the same vessel at the same time.

The most important thing to keep in mind when employing the use of a hospital or quarantine tank is, know your fish , know your chemical, and know your water.

Hospital Tanks: It’s a little difficult to talk about managing and maintaining a hospital tank without incorporating ancillary info and other considerations.

Some of these are:

  • Tank size needed.
  • Type fish. Tank set up.
  • Filtration.
  • Water parameters.
  • Medication characteristics.
  • Personal resources and time allocation.


Tank size needed is pretty much regulated by the type and size of the fish that is going to be treated. Obviously, a 10 inch fish is not going to fare well in a 10gal tank.Tank set up is pretty much straight forward. A bare-bottomed tank containing an upturned clay flower pot is really all that is needed under water. This would provide some security for the fish in a strange, new environment. Overhead lighting for the tank is not needed if there is sufficient light to be able to observe your fish. If not, then a small overhead light (preferably florescent) should be used.

Filtration is also pretty much straight forward. A small hang on power filter with mechanical media is all that is required. Since meds are likely to be administered, they would render the bio media useless. 100% water changes should be made at least once each day. Sometimes more.


Water parameters should be new, clean tap water. Unlike quarantine tank parameters, which will be discussed below, dechlorinated tap water heated and maintained at a desired temperature is recommended. Again, keep in mind that managing a hospital tank will require 100% water changes once or more each day.

Hardness and pH should then be adjusted to match water that the fish is being transported from. Water parameters will have a affect on certain medications. I’ll list some examples shortly.

Medication characteristics in relation to your water parameters will have an impact on the medication effectiveness. (Gratzek, John B., DR, University of Georgia, Vet Medicine), “The pH of the water during therapy may also be of practical importance in antibiotic absorption.”

“Depending on the chemical composition of the antibiotic molecule, it will dissociate (ionize) at either high or low pH, and in this form it is less likely to be absorbed by the fish.” “For example, a naturally acidic molecule such as naladixic acid will remain non-iodized is slightly acid water, and absorption will be expected to be maximal, if pH is adjusted to just under 7.”

“Water hardness also may affect antibiotic absorption.” “For example, calcium ions in hard water bind to tetracyclines, resulting in failure or the antibiotic to be absorbed.” “Solutions to this problem include either increasing the dosage or softening the water.”

Personal resources and time allocation would fall back to something that I discussed in a previous chat presentation (Non-growth ). Hospital tanks need to be ‘micro-managed’. One must be able to dedicate the extra time involved in its management.

Since most antibiotics are effectively absorbed by fishes within a relatively short period of time, 100% percent of water should be changed as often as two, but at least once each day during treatments. Treatments should continue several days after symptoms have dissipated and fish are acting back to normal.

And of coarse, one should be able to afford the costs of employing a hospital tank when the need arises. Tank, extra heater, meds, water conditioners, etc.

Quarantine tank(s): is a aquarium that imposes a period of isolation to lesson the risk of a contaminant which may spread to the main tank. In a quarantine tank, fish are allowed to acclimate and or recuperate from the stress of transport.

Managing a quarantine tank is not difficult and is only limited by your personal resources and time allotted for the acclimation of your fish or plants. I guess it can’t be that easy to sum up, so I’ll provide some ideas for set up and management of a quarantine tank for your consideration:


  • Size tank needed
  • Type of fish isolated/acclimated
  • Set up
  • Filtration
  • Water parameters
  • Personal resources and time allocation


Tank size needed: is generally 25 % the size of the destination tank. This may also have to be redressed to accommodate the size, type of fish, and/or the amount of fishes to be quarantined.Type of fish: would have to be of reasonable and practical species that is considered a aquarium fish. In other words, one that is likely to be kept by hobbyists and reasonably available for sale or trade.

Set Up: If you keep your main tank water maintained well, then I could personally see no reason not to fill at least 50% of your quarantine tank with water from your main tank. Top off with dechlorinated tap water and heat to the temperature of your main tank.

A single layer of neutral gravel can be laid on the bottom so fish will not lose their perspective. Plants that do not need to be rooted can also be placed in the tank.

Filtration: is a matter of pre planning. Biological media should already have been prepared and ready for placement in a power filter or canister filter. The use of a under gravel filter is not recommended for a quarantine tank due to the possibility of it becoming a hospital tank over the course of acclimation.

Water Parameters: recommendations here are going to get me in trouble here with a lot of folks.
Because you are acclimating a fish to the conditions of your main tank water, in effect, what you are doing at the same time is ‘adjusting’ the fish to surroundings that it will be moved too.

As you monitor water parameters in your main tank, you must also monitor current conditions in the quarantine tank. Check before and after a water change in the main tank, then increase or decrease quarantine tank conditions accordingly.

Water ‘adjustments’ can be made with water conditioning products such as buffers and pH adjusters. It is short term, so no great harm will become of this. OK, I just said it..lol. Its OK to use chemical additives to the change water for your quarantine tank.

Personal resources and Time Allocation: depends again on your power, authorization, , need and desire. Quarantine tanks do not need micro-managing as hospital tanks do, but they do require a commitment of your time and discipline. That discipline being not jumping the gun by introducing your fish too soon. How soon though really depends on the original condition of the fish.

Some info may need to be redefined if needed and not meant to supplant info already presented. It may be a bit ‘aged’ but most still sound. I gleaned this info from a presentation I gave to a local aquarium society about 13 years ago

5/5 - (15 votes)


Please enter your comment!
Please enter your name here