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When to use quarantine aquarium

Quarantine aquarium

Have you ever wondered what are the causes of snails plague in the aquarium or why fish catch diseases while being closed in well-maintained fish tank? Usually such situations take place because of external circumstances such us newly purchased fish or plants. If you want to avoid unpleasant struggling with unnecessary issues, read this article to know how to set up a quarantine tank!

quarantine aquarium

Why do we need to set up a quarantine tank?

We can divide the causes into two groups:

-new fish, snails or plants that are going to be introduced into the main tank

-old fish with disease symptoms

The source of fish diseases is usually introducing newly purchased fish into the main aquarium. Symptoms of the disease are usually not visible at the beginning but often after 2-3 weeks. And then almost nobody suspects that the cause is the new fish introduced to the fish tank a few weeks ago. If the new fish already infected the rest, the quarantine must be done anyway, otherwise we can lose the whole stocking. That's why it's worth to have a spare tank which may be used as the quarantine tank for new, hospital tank for sick fish or even the breeding tank if necessary.

New fish

Newly purchased fish should be quarantined for about 2-3 weeks before introducing them into the main tank. During the quarantine period, they should be carefully observed if the don't show any disturbing signs such as rubbing against the objects. Remember that the water conditions should be very similar to the water parameters of the water in which the new fish was transported. Of course, it should be introduced to the quarantine tank gradually because we don't want it to get shocked because of the temperature or differing pH. The water should contain about 70% of the water from the main tank and 30% of fresh water. This will help the new fish to acclimatize to the new environment without great shock in terms of the pathogens already present in the water. And of course the quarantine tank must be fully cycled. Read more about the nitrogen cycle in our BLOG.

New plants

Live plants can be the source of unwelcome parasites as well. Usually they are also the cause of the pest snails plague. To avoid struggling with them in the main display, always examine them visually to detect snails or their eggs. It is best to store a new plant in any container filled with demineralized water for a minimum of one week before placing a new plant in the main tank. Before that, you can (depending on the delicacy of the plant) rinse it with a disinfectant, e.g. chloramine or potassium permanganate. The risk of introducing unwelcome guests to the tank is lower when buying aquatic plants fromin vitro cultivation. They are grown in sterile conditions which means that they are much healthier and free from pests.

New snails

Newly purchased snails should be quarantined as well. They may be the carriers of infections that are very dangerous to fish, for example ich. The quarantine should last at least a week. For this purpose, a small glass vessel or tank can be used.

Sick fish

Quarantine fish as soon as you can see any uncommon behavior such us rubbing against different objects, changes in their appearance or poor appetite. The last thing any aquarium owner wants is the chain reaction. Especially that in case of fish, different symptoms of different diseases develop differently in different species. Infected fish should be moved to the hospital tank. The hospital tank works best without any substrate or decorations because it's easier to keep it tidy and therefore maintain good water quality. During the quarantine period, closely observe factors such as excrement, appetite, behavior, fin and skin condition.

Also if any infection in the main tank was detected, a big water change should be done in the main aquarium. The sick fish in the quarantine tank should be carefully observed and if the symptoms are not visible anymore for a few weeks, it can be moved back to the main aquarium. The water from the hospital tank should not be poured into the main display and the aquarium glass and equipment should be disinfected before starting another treatment session.

Equipment for the quarantine tank

As mentioned before, the quarantine tank works best without any substrate, decorations or plants. Therefore it's easier to control the water quality and take out excrement and uneaten food. Moreover the observation is facilitated because due to the lack of hiding places, you can keep your eye on the sick fish constantly.

Secondly, the quarantine tank should be equipped with an effective filter compatible with the size of the tank. The type of the filer is not important here.

Test kits, thermometer and heater will be helpful as well to maintain stable water parameters. It's important in particular in case of fish with already weakened immune system (due to transport or disease).

And last but not least, any tools used for quarantine tanks maintenance should NOT be used in the main display tank. They should be disinfected every time after contact with the tank water from the quarantine tank.


If you don't want to introduce any unwelcome infectious disease to your display tank, quarantine new fish for about 3 weeks. In case of plants, observe them and take off any pests from the leaves. If possible, buy fish, snails and plants from reliable sources and avoid live food. Remember about regular water changes. Do not hesitate to move weird-behaving fish to the separate tank before more fish get infected.