Quarantine Tanks

That Pet Place


3/8/2018 2:42 pm

Setting up a Quarantine Tank

A quarantine tank is simply a small aquarium that is set up for the purpose isolating a fish, or fishes, from your display aquarium. Quarantine tanks are inexpensive and easy to set up, and are an investment in protection for your aquarium.

Parasites, injury, and infectious disease are an unfortunate and unavoidable aspect of the aquarium hobby. One of the main purposes of a quarantine tank is to hold new fish purchases in an isolated tank that allows for easy observation. If the fish should show signs of parasites or other infections you can medicate with no risk of infecting the fish in your main tank. A quarantine tank also gives new fish an opportunity to get used to processed food without having to compete with your established fishes that most likely are aggressive eaters. Another benefit of a quarantine tank is that it also gives you somewhere to put injured or aggressive fish that you may need to remove from your display. For a suitable quarantine tank, all you need are the following:

Tank - ten to twenty gallons is usually sufficient, depending on fish size

Filter - anything from a simple sponge filter to a small power filter depending on the type of quarantine system you wish to use

Heater - essential to tropical and saltwater systems but unnecessary for goldfish

Hideout, Plastic Plants, Aquarium Ornament - not completely necessary, but will reduce stress by giving the fish a place to hide and feel more secure

Creating & maintaining a quarantine system has a number of advantages.


Just like people, fish get stressed out when they are suddenly thrust into a new environment, and this stress only increases in the presence of other fish. A quarantine tank allows your fish to "come down" from that initial home stress, making it healthier to cope with life in the main aquarium.


Transporting or moving fish is a stressful time, and often leads to disease. Fish commonly contract bacterial infections, fungal infections or parasitic infections after coming home, and you don't want to spread these to your other fish. In addition, an isolated sick fish is much more economical, quicker and easier to medicate than one in a large display tank. Many common fish medications, such as copper or formalin based, are detrimental to other tank inhabitants as well as biological filtration.


There is no better way to ascertain the health of a fish than simply by watching it. Large display tanks can have lots of nooks and crannies for fish, especially stressed ones, to hide.

Controlled Feeding

Controlled feeding is another important function of a quarantine tank. Wild caught fish can be very slow to acclimate to prepared foods, and may be very timid towards accepting new types of foods. Without competition new fish get a chance to adjust at their own pace, allowing them to compete once they are ready for the display aquarium. Use of appetite enhancers, like garlic, can also aid in training finicky fish to accept new foods.

Quarantine of new fish should last for at least 21 days, this allows for extended observation, and for any parasites that may be present to complete their life cycles. If after 21 days there has been no sign of parasites or disease it is safe to acclimate and introduce your new fish to its permanent home with minimal risk of introducing any pathogens into your display. If at any point during quarantine you suspect there may be a problem with your fish, and you decide to medicate, your quarantine "clock" must be reset and you should start the 21 day period over again. Many parasites have multiple life stages, most medications are only effective against specific stages. For this reason, only an extended exposure to medication is truly effective against many parasites. This is also why some parasitical problems seem to come and go, the parasite may only become visibly apparent at certain life stages, although they were there all along.

There are two main types of quarantine systems, permanent and emergency. Permanent systems are highly recommended because they are more stable, but emergency systems will work in a pinch if properly maintained.

Permanent Quarantine Systems

Permanent systems remain set up and established all the time, whether a fish is being medicated or not. This allows for a stable environment closer to that of the main aquarium, but requires space and time for it to be maintained. This type of quarantine tank should be equipped with a small power filter or canister filter, and water conditions kept similar to the main tank. Ideally, the filter should allow for easy removal of the chemical media (carbon, zeolite, etc) while medicating. The tank should be maintained regularly as well. Frequent water changes and algae maintenance after cycling will keep the tank healthy and ready for new arrivals or ailing fish. Hardy fish like danios or plecos (for freshwater) or mollies and damsels (for saltwater) will keep tthe tank cycled and stable between uses. When adding new fish to these systems, the fish should be slowly acclimated to the new tank as water conditions will be different from their previous tank.

Emergency Quarantine Systems

You do not need to keep your quarantine tank running when not needed if you are limited on space. The emergency quarantine tank is one that is set up as needed. While not as stable as a system that remains established, these systems are good for isolating and medicating sick fish, or as a temporary home for a new or displaced fish.

When needed, fill your quarantine tank with water from your display, this accomplishes a water change in your display, as well as gets you started with conditioned water in your quarantine tank. Another good trick is to keep your sponge filter, or cartridges from your power filter in your display tank. This keeps them colonized with bacteria and you will not have to worry about cycling your quarantine tank if you need it in a hurry. This is very easy to do if you use a wet dry filter on your display, simply hide them in the sump until they are needed. You can set up an instant established quarantine system in just a few minutes if you plan for it.

These tanks also do not require starter fish to maintain the nitrogen cycle because they are cleaned out after each use. When cleaning, it is important to remember not to use harsh chemicals like Windex, or other cleaners. If disinfection is necessary, a very dilute bleach solution can be used. Just make sure to rinse the tank thoroughly after using the bleach water, and allow the tank to dry thoroughly before using it again.