Why do we need a Quarantine Tank (Hospital Tank) for aquarium fish, and how to set it up.

Some fish hobbyists call it a quarantine tank, while others call it a hospital tank. Whatever you call these fish tanks with basic setups, they have special purposes – to quarantine new or sick fish.

Why do I need a quarantine tank?

1. To Quarantine New Fish Before Introducing them to your Other Fish in the main aquarium
There are hundreds if not thousands contagious fish diseases and parasites out there. e.g., Ick, fluke, mouth rot, etc. just to name a few. We are not trying to scare you if you are new to the hobby. It is very rare any fish disease or parasite can affect a human, but the danger is very real to your existing healthy fish.

Whenever you buy one or more new fish, you might introduce some unwanted diseases or parasites into your well-established aquariums. All it takes is one sick fish to affect the whole system. Although some fish might look healthy when you just bought them, the symptoms of the diseases or parasites might not show up until after they are introduced into your aquarium. By then, it would be too late. You might end up with a tank full of sick fish or even worse just because of this one disease/parasite-carrying fish you added. Risking a loss of all your beautiful fish each time you add something new is not worth it. It doesn’t mean you can’t add new fish to your existing fish tanks. This is when you need a quarantine tank.

As experienced fish hobbyists, we highly recommend to quarantine all new fish in a separate fish tank for no less than 2~3 weeks. Most fish diseases and parasites should show symptoms on the fish within this period. To be safer, you may quarantine the new fish longer as you wish. If the new fish show no symptom of any kind for over a month, you may safely introduce the fish to your main/show tank. If the fish show any disease or parasites, you can treat it accordingly in the quarantine tank without affecting your fish in the main aquarium.

2. To Treat the Sick Fish before returning them to the main aquarium
Sometimes healthy fish can still get sick even when you have not introduced anything new for a while. It can be the result from an injury or an infection. Sometimes an infection can be contagious. You want to separate any sick fish from your healthy fish as soon as possible. This is what a quarantine tank for. Now acting as a little hospital tank for the sick fish.

There are many fish medications out there for most of these problems. However, many medications have side effects, and some of them are not only hard on the fish, but they might also even crash the aquarium nitrogen cycle by killing the beneficial bacteria in the aquarium filter system. You need to relocate the sick fish to their tanks if you do not wish to treat the whole tank of healthy fish for just one sick fish or risk crashing the nitrogen cycle.

It is also more economical to treat sick fish in a smaller tank. For example, you can achieve the same concentration of medication in a 5-gallon tank with only half the dosage as opposed to a 10-gallon tank.

How to set up a quarantine tank?

Unlike the main aquarium for showing off, you will only need a few basic equipment for a quarantine tank setup.
1. A fish tank
2. An aquarium filter
3. An aquarium heater
4. A thermometer
5. A separated set of fish net
6. An aquarium vacuum
7. A water bucket

A quarantine tank does not require any gravel or decoration, but it won’t hurt if you have some extra to spare. Fish might feel less stressed in a fish tank with some decorations than in an empty tank.

As a quarantine tank, it should be smaller than your main tank. A 10-gallon tank should work fine unless you have large fish. A 5-gallon tank is perfect if you only keep small fish for less than 3” long.

Just like any aquarium, a quarantine tank requires a cycled aquarium filter system. You can solve this easily by having a small sponge filter running in your main tank which can be relocated into a quarantine tank when needed. You may also keep the quarantine tank running by keeping a few healthy fish in there and transfer them into the main tank to make room for the new fish when the time comes.

An aquarium heater and a thermometer are needed if you are keeping tropical fish.

One extra air tubing, air valve, and air stone can also be useful if your existing air pump can provide another split. The air stone is not needed if you use a sponge filter for the quarantine tank.

Important: You should have a separate set of fish net, an aquarium vacuum, and a water bucket for the quarantine tank because these media can also transmit fish diseases and parasites. Likewise, you should wash your hands every time after you have worked on the quarantine tank.

By having a quarantine/hospital tank, you keep your existing fish safe from unwanted parasites and diseases. It saves you the trouble and money in a long run. A basic 5 to 10-gallon quarantine tank setup can be had for under $50. This might seem to be a lot if you only have a 5 to 10-gallon main aquarium, but for those who have one large or multiple aquariums and get new fish fairly often, it is absolutely worth the cost. Some expensive fish can have the price tag of more than $50 each. This is especially true for saltwater aquariums. Therefore, it is more critical for saltwater aquarium hobbyists to have a quarantine tank.

Related Posts

6 thoughts on “Why do we need a Quarantine Tank (Hospital Tank) for aquarium fish, and how to set it up.

  1. Thank you for this article. I’m a beginner. If I remove a single betta from an established 5 gallon cycled tank to quarantine, will the 5 gallon tank’s cycle crash while there’s no fish in it? Will I need to do something to maintain the cycle, or will it be fine untouched for a week?

    • Without a source of ammonia, the cycle will crush since the good bacteria will be left without food. In the absence of the fish, the only way to keep the cycle is to add a source of ammonia. Be it pure ammonia, or some fish food. I have actually done just that… putting a cycled sponge filter in a bucket of water without a source of ammonia, and bacteria colony died off within a week.

  2. Well if your tank is 30 gallons you will have to ditch those bala shakrs and pictus catfish.insted get -2 paradise fish-2pearl gouramis-2honey gouramis- 10 harquelins-10 amano shrimp if you have these fishes you will havea wonderful asain community and a balanced tanl.dont get anything from the amazon biotopes they do not go well with asian fishes.the amano shrimp will not get eaten and cleans algae.you can replace the pictus catfish with 2 or 3 asian glass catfishes.and DO NOTGET APPLE SNAILS THEY WILL RUIN THE PLANTS AND MIGHT KILL SLEEPING FISH if you want to add snails dont do it they will breed like rabbits and destroy yur live plants.plants suitable for a asain biotpe will beHygrophilajavafernbamboo plantwater wisteriaany crytocorynesI’ve had aquariums for several years

  3. Question: If you have set up a hospital tank & then treat the sick fish, fish comes good and can be reintroduced back into your main tank: 1.) Do you need to take all the water out of the hospital tank and start a new cycle with clean fresh water? 2.) Will the filter clean up the hospital tank medicated water, once testing shows water is clean and healthy again you can pop a small fish back into the hospital tank to keep the cycle turning over?

    • Hi Sue,
      If your filter system has activated carbon in it, then it will clear up the medication. If not, you can relay on water changes. Filter bacteria will not die if you keep the filter media wet during the water change. Yes, you can keep a small fish or two in the hospital tank to keep it cycled. Or, you can simply move the filter from the hospital tank to the main tank to run along side of the main tank’s filter to keep it cycled.

      • Thank you very much for getting back to me. I am only three weeks into my 20lt hospital tank cycle. Ammonia has just started to show with a reading of 0.25ppm so have at least another four weeks to go before tank is cycled, but I’m not in any rush, just as long as none of my fish in my main tank become ill in that time (All looks good with main tank all readings a spot on). I am running activated carbon in the two filters on the 20lt tank. I also have two canister 600lt filters running on my 75lt tank, so unfortunately I can’t fit the two small filters into my 75lt tank as the back opening is taken up with my two canisters. Once the hospital tank is finished cycling I’ll purchase 1 x male & 2 x female guppies, and that can be there home. Thanks for the advice and help – Cheers Sue

Leave a Reply

Your email address will not be published. Required fields are marked *