A word of caution there is no guarantee that you will get a fish that is disease-free when you buy it from a breeder, local fish shop, or even Petco. So it is important to quarantine a fish before it is introduced in the aquarium. This quarantine process will save the life of your favorite fish and also prevent any spread of pathogens to your aquarium. Keep reading to understand why it is important and crucial to quarantine a fish.

Why is it important to Quarantine a fish?

Quarantining new fish is an extremely important step in keeping your new fish happy and healthy.

A fish’s immune system should be able to fight off more infections and diseases, however, the shock of transportation compromises your fish’s immune system leaving it vulnerable to any disease that gets shipped with it. Some of these diseases when they break out can be so deadly, they can wipe out your tank within days.

 That even healthy fish carry some pathogens, the reason they don’t get sick is that their immune systems are able to keep them in check. But fishes are under stress when they’re bounced from fish farm to wholesaler to retailer to a hobbyist’s tank. Fish Quarantine is not just to prevent disease and let the fish accumulate to new surroundings, new ecosystem, and new fishy friends

Benefits of fish Quarantine

Below is the list of benefits when you quarantine the fish

  • When you quarantine a fish it gives them a chance to settle down and gives their immune system a chance to relax and regenerate.
  • Quarantine fish will help minimize the potential spread of infectious disease to other fishes.
  • Wild-caught fish can be very slow to acclimate to prepared foods, and maybe very timid towards accepting new types of foods, and the quarantine process would help them adapt to prepared food.
  • Would help condition new fish to new water parameters with a stress-free environment.

As we know the benefits of quarantine a fish, let us move on to setting up a quarantine fish tank

How to set up a quarantine fish tank

A quarantine tank is the first step for safeguarding our new friend, so it should be very comfortable to them, usually, 10-20 gallons is enough but big fish need more space so depends on the fish choose the size of the tank for good results.

Required supplies

  • Heater (when dealing with tropical fish)
  • Air pump
  • Fish medicine and foods
  • A power head for surface agitation

Required tools

  • Fish catching net
  • Ph level test kit and Temperature kit

Total cost: USD 50


Total time: 7 days

  • Choose the right quarantine tank size

    A 50-to-100-gallon tank will suffice for goldfish and smaller koi, if you need a tank for larger koi (above 15 inches) then you may want a 200-to-300-gallon tank

  • Setting up the quarantine fish tank

    Wash the quarantine tank with only hot water without adding any soap or chemical liquid/powder because chemicals may be allergic to fishes.

    ✦ Add new distilled water that you’ve treated and fill half of the quarantine tank with water from the main tank so that it has similar properties.

    ✦ Add the filter, heater, powerhead, and aerator (either an air stone or air pump) and turn on everything.

    ✦ Place a few decorations and hiding spots can also help your fish feel more comfortable in their new surroundings. Test the chemical levels and ph levels in the water and make sure nothing is out of balance.

    ✦ Try to keep the quarantine tank at the same temperature as your main tank, as you will eventually be transferring fish between the two.

    ✦ If your filter uses carbon, remove the carbon as it can lower the effectiveness of medications

  • Quarantine Tank Environment

    Make sure that the quarantine tank environment is the same or close to your main tank can maintain the vitality and health of your fish and their offspring


A quarantine tank in a fish room will save a lot of dollars and lives of your cared fish pets

Now that we know how to set up our own quarantine tank, it is important to know how long we should quarantine a fish

The ideal quarantine period for a fish

A fish quarantine period depends on whether it’s a newcomer to our aquarium or it’s our old friend but a little bit sick need special care.

  • A newly brought fish should be quarantined for at least 21 days or 2-4 weeks. Quarantining a fish is to make them relax from the transport shocks and set with our surroundings
  •  A sick fish should be under treatment for 2 to 3 weeks. During that time, they often monitored and treat for bacterial infections if there are obvious symptoms (ragged fins, red spots, etc.). Make sure to perform a water change every other day to keep the inhabitants of the quarantine tank healthy.

If the fish is brought from a pet store don’t let fish straight to the main aquarium with brought water we don’t know whether the store water is the same as our aquarium.

By now you know the duration of the fish quarantine period. let’s understand the steps involved to introduce a new fish to a quarantine tank

Steps to be followed before you introduce your fish to a quarantine tank

Introducing any pets to a new environment will shock them, but for fish, it is particularly stressful. Not only will a new aquarium tank be completely unfamiliar for your new fish, but the water will likely be of a different quality. Changes in water temperature, pH, and other factors make a huge difference in a fish’s life.

To keep your fish safe and healthy, there are certain measures you should take when introducing fish to a new aquarium tank.

Below listed are some tips on how to make an easy transition

Transport bags tend to be clear plastic bags, with a length three times the width of the bag. In any professional aquatics store, about 30 percent of the bag will be filled with water

  • Take the sealed bag that your fish came in and float it on the surface of your quarantine tank water.
  • Allow the bag to sit for ten minutes, then open the bag and add a cup of your quarantine aquarium’s water to it. Reseal the bag and let it float again for ten minutes.
  • Repeat the previous step until the bag is full. Rest it for 10 minutes
  • Carefully submerge the whole bag into your aquarium and slowly wait to let the fishes swim out of the bag by themselves.
  •  Do not pour the fishes into your aquarium quarantine tank as this will create tremendous stress on the fishes and some of the more sensitive breeds might not be able to survive through this ordeal.
  • Do not feed the newly introduce fishes for the first 24 hours as it takes some time for the newly purchased fishes to get acclimatized to the new environment.
  • When introducing fish to a new environment, any sudden changes can send them into a state of shock and weaken their immune systems.
  • The various properties found in water are partly responsible for this, along with the temperature of the water.
  • pH levels, salinity, and hardness (the number of dissolved minerals) vary from tank to tank, meaning that water in a new aquarium will take some getting used to.
  • Therefore, to accumulate fish properly, a few steps need to be taken to make a warm welcome for the little guys.

Now that we know how to introduce the fish to the quarantine tank, let’s understand the fish quarantine medication process

Treat the most common fish diseases and treat them in the quarantine tank

If a fish quarantine is for hospitality make sure tank is sterilized, being able to recognize problems and begin treatment early gives you the best chance of saving your fish

Below is the list of common diseases and treatment method

Disease NameSymptomsTreatment
ICHwhite spots on the fish and rapid breathingIch is a very common disease this can also be treated with aquarium salt or un-iodized salt in raised water temperature
DropsyBloating of fish stomach due to indigestion infection, scales will stick out from the bodyA good antibiotic, quarantine with raised water temperature
Marine velvetRespiratory disorder, dusty appearance on body, Loss of appetite, Rubbing against decors on the aquariumTreat with copper in quarantine tank in low salinity
CostiaBristling of scales, scarping, heavy mucusIt can be treated with copper at 0.2 mg per liter to be repeated once in a few days. Can also be treated by adding aquarium salt
Hexamitahole in the head, the color of fish change to black, slimy, white mucus, even while eating and acting normal. Fish will be hiding in the corners, the eyes get thin, and swim backwardquarantine a fish and treated with antibiotics and improving the water quality, improve the food quality with high nutrition, good mineral and vitamins
ChilodonellaDiscoloration of fish due to excessive slime, weakness, gill damage.Good quality of water with activated carbon filter


As a hobbyist, if you don’t have a quarantine tank or have not thought about fish quarantine, well post reading this post I am sure you understand the importance of fish quarantine and what is required to set up a quarantine system at home.

Believe this post has covered every aspect of quarantine fish, and if there any other questions don’t wait just leave your comment and will be more then happy to answer them


Here is what some of the experts share how they quarantine their fish