How to Set up an Aquarium Quarantine Tank

Aquarium quarantine tanks are used to monitor new fish or corals and treat sick fish or sick corals. In either situation, it’s a good idea to have an established aquarium set up so that in the event that you need it, it’s stable and ready to go! Some people suggest that you use a quick cycle product and set up the aquarium to be used within a few hours. I disagree because new systems that are not already established can stress a fish out even more. Especially if the fish produces a lot of waste, this could create a senario where an already sick fish or coral now needs to endure a tank cycle – not good. So if you are going to be observing new fish or corals from time to time or you want to have a system already set up incase you need to treat a fish, coral or invertebrate for any reason – this is what I recommend:

Tank Size

Depending on the size of the fish, corals or invertebrates that you will be quarantining will determine your quarantine tank size. A 20 gallon long aquarium is a good start.

20 Gallon Long Aquarium

Remember, a typical quarantine period could be anywhere from 30 to 60 days. So you want to make sure that the tank will be large enough for the fish or invert for that period of time. You also want to get a proper lid that allows for gas exchange and also prohibits the fish or invertebrates from jumping out.


I recommend both a canister filter and a hang on filter. The canister filter will provide a good source of biological filtration while the hang on filter can be used for carbon in order to remove medication as well as filter floss for general mechanical filteration.

Hang On Filters

The canister filter should not have any filter pads or bags of carbon in it so that it does not remove the medication that you add to the tank. This also allows for more space for biological filtration media.

Canister Filter


Just as a stable bio load is important to helping the fish, coral or invertebrate regain it’s health, a stable temperature is also essential. For your heater, you want to get one that is within the 3 to 5 watts per gallon rule. Titanium heaters tend to be the most popular and safest solution. Be sure to have something that will prevent the fish from coming into direct contact with it as they can get burnt by making contact with it. Here is an example of a titanium heater by Finnex that comes with a guard:

Titanium Heater With Guard


Even though most heaters have their own built in thermometers, it’s always good to have an additional one to ensure that the tank is the correct temperature.

Digital Aquarium Thermometer


A light source will allow you to monitor the fish or invertebrates and provide a light cycle to further help promote good health. A simple LED strip light will suffice for fish and invertebrates.

Basic LED Aquarium Light

If you are going to be quarantining corals, you will need a proper lighting solution for them depending on the species.

Test Kit

Just like any other aquarium, you will want to test your water parameters in your quarantine tank to ensure that your water quality is good.

I use API for both my freshwater and saltwater tanks.

API Freshwater Master Test Kit
API Saltwater Master Test Kit

Some people like to use the monitors like these to ensure that they know at a glance what their tank’s water parameters are at any time:

Seachem Ammonia Alert


Because you may need to treat the fish with medication, I do not recommend using a substrate. A substrate will absorb the medication and make it difficult to completely remove it from your tank. A bare bottom tank will also allow for easy clean up with a siphon for simple maintenance.

Decor/Hiding Spaces

A lot of quarantine tanks contain a ceramic pot or two. These make great hiding spots while allowing you to still view your fish or invertebrates. PVC pipes are also a good quarantine tank d├ęcor option.

Quarantine Tank With Flower Pot

The trick is to use something that you can easily clean that will allow the fish or invertebrate to have a good place to hide as well.

So how much will it cost you to set up your quarantine tank? Let’s price out the 20 gallon long quarantine tank:

  • 20 Gallon Long Aquarium – $20
  • 20 Gallon Long Aquarium Stand – $60 – $100
  • Hang on Filter – $30 to $40
  • Canister Filter – $50 – $100
  • Aquarium LED Light – $20 to $30
  • Digital Thermometer – $5 – $10
  • API Master Test Kit – $20 to $40
  • Seachem Ammonia Alert – $20

~$225 on the low end and ~$460 on the high end. In the end, the investment is totally worth it as you will be not only saving lives, but saving a bunch of money along the way! Let me know in the comments below what fish, coral or invertebrates you keep that you are going to set up a quarantine tank for.

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