How To Quarantine Sick Fish? (Step by Step Guide)

If you have a sick fish, there are a few things you can do to help it get better as quickly as possible.

The best way to prevent the spread of fish disease is by quarantining sick fish in a separate tank. The quarantine can be done in a variety of ways, but all methods have one common goal: to separate healthy from sick fish until the sick fish can be cured or killed.

By doing this, the fish can get the attention it needs without spreading its illness to other fish in the tank. There are also a number of products available that can help to quarantine sick fish.

Related: How To Quarantine New Fish?

Related: How To Quarantine Saltwater Fish?

How Long Fish Keep in Hospital Tank

This tank is mainly a backup tank for quarantining the fish. The hospital tank must be set up to match the circumstances in the main tank so that the fish can move in the hospital tank causing the least amount of stress on fish.

New Zealand has a minimum quarantine time of six weeks for exports of freshwater ornamental aquatic animals and three weeks for marine ornamental aquatic animals, while Australia requires 7–21 days for freshwater ornamental finfish and 7 days for marine finfish.

The length of time fish must stay in this hospital tank is determined by the species and condition of the fish. The fish were kept in a 114-liter hospital tank for seven days to recover.

How To Quarantine Sick Fish?

The best way to prevent the spread of disease in a fish tank is to quarantine any new fish before putting them in the tank. This means keeping them in a separate tank for a period of time to make sure they are healthy.

If you see any signs of illness in a fish, you should isolate it from the rest of the fish and treat it with medication.

Here are the necessary steps for quarantine sick fish,

Step 1: Check the hospital tank carefully

Check the hospital tank for leaks and fill two buckets with water. The water should be dechlorinated and should match the habitat quality.

The buckets are at least 2.5 gallons (9.5 L), but larger fish require 10 gallons (38 L) in aquariums. Make certain the containers are well-aerated.

Step 2: Keep the fish with an appropriate chemical dose

Move the ill fish to the first bucket with the net. For 10 minutes, add 3/8 teaspoon salt per gallon (0.5 g/L) every two minutes.

Transfer the fish to the next bucket of fresh water using the net for 30-45 minutes. After 15-20 minutes, add another 3/8 teaspoon salt per gallon (0.5 g/L).

Step 3: Move the fish into the hospital tank

Move the fish into the hospital tank using a net. Make sure to replace the water every day (30-50 percent).

After one day, transfer to a shallow, transparent bowl. Inspect the fish for parasites and illness signs. Use a magnifying glass if needed.

Step 4: Treat the water as needed

Treat the water as needed. Isolate the fish for at least 10 days.

Related: How To Quarantine Shrimp?

Related: How To Quarantine New Aquarium Plants?

How Long to Quarantine Sick Fish

The sick fish should be kept in the quarantine tank for a minimum of two weeks, although three weeks is often recommended. This will give the fish enough time to recover and hopefully won’t infect any other fish in your tank.

Fish can get sick for a variety of reasons: poor water quality, injuries, and even parasites or diseases. If you notice that one of your fish is acting oddly or is swimming erratically, it might be time to quarantine it.

Quarantine tanks should be set up with clean water and no other fish in order to prevent the spread of illness.

Tips for Quarantine Sick Fish

-Consider the sick specimen, and stress, ailing behavior, disease, and death in aquaria are all environmental issues.

-Check the pH, ammonia, nitrite, nitrate levels, the oxygen content, if possible.

-If these are satisfactory, ensure that no other contaminants, like paint fumes, insecticides, or cleaning chemicals, have spread to the tank.

-Double-check that all accessories are working properly. Ensure layout of the tank and food habits because the layout and feed inadequacies can both have an impact on the fish’s health.

Quarantine Sick Fish Without a Tank

One of the most important things you can do to maintain the health of your fish is to quarantine any new arrivals.

This means putting them in a separate tank for a period of time to make sure they are not carrying any diseases that could infect your other fish.

If you don’t have another tank, you can quarantine sick fish by using a bucket or a large container. Put some water from your tank in the container and add a heater if necessary to maintain the temperature at around 75 degrees F.

Place a filter in the container and add some aquarium salt (1 tsp per gallon). Put the sick fish in the container and monitor it closely for signs of improvement.

Related: How To Setup A Quarantine Tank?

Related: Biosecurity in Aquaculture


  1. Hadfield, Catherine A., and Leigh A. Clayton. “Fish quarantine: current practices in public zoos and aquaria.” Journal of Zoo and Wildlife Medicine 42.4 (2011): 641-650.
  2. Arthur, James Richard, Melba G. Bondad-Reantaso, and Rohana P. Subasinghe. “Procedures for the quarantine of live aquatic animals: a manual.” (2008).