How to Quarantine Fish

Congratulations on getting your new fish! We know that it’s very exciting but wait! In order to ensure your fish is healthy and happy for the long run, a few measures need to be taken.

Why do we need to quarantine our new fish?

Quarantine is done as a preventative measure. More often than not, our new fish is stressed out due to shipment and overcrowding inside the tanks or aquariums at the warehouse and your local fish store. This causes their immunity level to drop greatly, causing them to be more susceptible to diseases.

What if you received a fish from a friend? We would still recommend to quarantine your new fish. You do not want to risk transferring anything bad from your friend’s aquarium (no offense) into your aquarium. Better be safe than sorry!

Quarantine is detrimental for both the health of your new fish and for the fish inside your established aquarium. We want to prevent a disease outbreak as much as possible!

Basic Quarantine Set up:

  1. Aquarium/Tub/Bucket : Anything that holds water and that is big enough for your fish.
  2. Dechlorinated water : Treat water with a dechlorinator or anti-chlorine if you are using regular tap water.
  3. Filter : Use mature, cycled filter media or sponges to “instant cycle” your quarantine container. If you do not have any, daily 70 – 100% waterchanges with Seachem Prime is needed. Try to mimic similar aquarium parameters as the aquarium you are planning to keep your new fish in.
  4. Air Stone : Keeps the water oxygenated. It is optional if you have a filter with good flow and your quarantine container is well aerated.
  5. Test kit : Good water parameters is VERY important for fish, especially new ones. Ensure your parameters are ; 0 Ammonia, 0 Nitrites and less than 20 ppm of Nitrates at ALL TIMES. (Read : The Nitrogen Cycle)
  6. Medicine : We, at BeFishy feel strongly about using medicine ONLY when it is necessary, especially antibiotics. You would want to monitor your fish first before dosing any appropriate medicine into your quarantine container. For instance, are there any visible white spots, cotton wool-like growth, red streaks or marks, exposed wounds, abnormal shape and behaviour, loss of appetite and etc. Generally, anything abnormal about your fish. If your fish is clear of everything, still monitor them for the next 4 weeks. Usually, new fish will exhibit signs of illness in the first week to 3 weeks.
  7. Prophylactic Treatment : Now, you might be wondering, hey! You’re contradicting yourself! Let us explain. Prophylactic treatment is done to prevent a certain type of disease. We recommend prophylactic treatment for Wild-Caught Fish. For example, Pufferfish. Pufferfish are mainly wild-caught. Wild-caught fish tend to have hitch hikers like unwanted parasites. As for pufferfish, they are very prone to internal parasites. In this case, a prophylactic dewormer medicine is needed. We recommend Levamisole Hydrochloride as a dewormer as it is effective against most common internal parasites.

“CAUTION : Not all medicine is safe for scaless fish & invertebrates”

What is the recommended quarantine duration?

We recommend to quarantine your fish for 4 weeks minimum due to reasons mentioned earlier. If you find any suspicious signs that your new fish is sick, definitely prolong your quarantine period until you are certain that your fish is clear from any diseases. Treat your fish with the appropriate medicine at the appropriate dosage accordingly. Please note that some parasites and pathogens have a longer incubation period more than others.


– Lights for a Quarantine Set Up?

Lights are definitely optional. Keeping the lights off or simply not having lights at all can help minimize stress for your quarantine fish.

However, when checking for any signs of illness, definitely check with a light source. You do not want to miss any major or minor signs of diseases.

– Do I need to perform waterchanges for my quarantine tank?

Regular waterchange schedule is to be performed as usual.

If your water parameters are off, definitely perform an emergency waterchange.

When treating with medicine, refer to medicine label for waterchange instructions.

– How do I quarantine sick fish?

The steps mentioned above are applicable to new and current sick aquarium fish.

We wish you a happy fishkeeping journey ahead!

Share This: