Fish Quarantine

Image this. You just bought a brand new fish. It looks ok and it acts normal. So you decide to give it the textbook quarantine—a separate tank for about 40 days. When all looks normal, it gets added in with the rest of your stock. A short time later, you notice a problem in your tanks. The fish look sick and many are dying. What happened?

You made one of the most costly mistakes a fish-keeper can possibly make—insufficient quarantine procedures. Let’s look at the mistakes more closely and then discuss how to do it right.

The first and most common mistake made when people quarantine is to assume that a fish in a separate tank is truly segregated from the rest of their stock. Remember, any link between the quarantine tank and your other fish is a means of spreading disease—even you. When you put your hands in one tank and then another, you are serving as a vehicle for any diseases in one tank to spread to another. Many people believe that washing their hands and arms with soap and water in between tanks will solve the problem. Not so. Short of soaking your hands and arms in bleach, you won’t kill everything on your skin.

So what can you do? The best plan of action is to take care of all business with your original stock first each day before going anywhere near the quarantine tank. After coming in contact with the quarantine tank, avoid contact with your other tanks for as long as possible—the longer the better, as fewer organisms will be able to survive the acidic, enzyme-packed environment that is your skin. And since you are going to such great lengths to make sure you transfer nothing on your skin, it goes without saying that you should never share equipment such as nets or buckets between your stock and quarantine.

Once you have two separate tanks set up, two sets of equipment, and a fool-proof system for avoiding consecutive contact—you’re all set, right? …Right? Here is where most people make the second mistake. They place the quarantine tank in close proximity to their other tanks—either in the same room, or even worse, right next to each other. Keep in mind, that one half teaspoon of water from an aquarium contains between 1 million and 1 BILLION bacterial cells. The next time you watch that bubble from your filter rise to the surface of the water and burst into millions of micro-droplets, know that each of those airborne micro-droplets can contain thousands of bacterial cells intent on infecting everything they can reach in no time at all. Distance is very important. Place your quarantine tank as far away from your other fish as possible.

The dictionary defines “quarantine” as a 40 day period. Most people assume that if they have been faithful to the guidelines above, and after 40 days the new fish still look healthy, they are perfectly safe to introduce to their stock. Here’s the hidden problem with doing that. Many fish may look and behave perfectly normal, and yet carry all sorts of diseases. They may carry a virus to which they are immune, a bacterium which to them is normal flora or benign—but to your other fish is a virulent pathogen, or any of a variety of sub-clinical problems. Even more common is for them to have a parasite that is low in number due to the fishes' strong immune system.  But how will you know? The best thing to do is to take a fish from your stock and add it to the quarantine tank. Observe it. Does it show any signs of illness? Is it still eating and acting normal after a week? If so, great—but, you’re still not done. The final step is to take another fish from your stock and stress it. Leave it in a bucket or bag it up for a couple days—creating an immuno-compromised state. Add this fish to the quarantine tank.  If, after a period of careful observation, it looks healthy—chances are it will be relatively safe to introduce the new fish to your stock. Should the above scenario result in either of your two stock fish becoming ill, or showing any other signs of abnormal behavior, the new fish should be considered unsafe and removed from your hatchery or home. Make sure to bleach everything which was exposed to water from that tank.

Keep in mind that quarantine works two ways. Your are not only protecting existing stock from pathogens carried by the newly acquired fish, you are also protecting the highly stressed, new stock, from pathogens that are in your prior existing aquariums.

The Quarantine Aquarium

There are several important steps to follow:

• The biological filter should be established without using fish.
• You should not use filter material from a tank that contains fish, unless you are absolutely positive that tank contains no pathogens (extraordinarily rare).
• The aquarium should have a tight fitting cover.
• You should only touch the water when necessary and only at the end of the day when you will not be near other aquariums anytime within several hours.
• Give the fish plenty of space so you can minimize the water changes needed. Changing water tends to spread pathogens to siphons, hands, shoes and other objects that may eventually come in contact with other items that are exposed to your other aquariums.

Proper quarantine is not an easy task. The excitement of new fish is usually enough for even the most experienced fish-keeper to forego our intense quarantine procedure (or any quarantine for that matter) and introduce them to their stock right away. Patience is required to avoid disaster. If you know that you don’t quite fit that mold, your best bet is to buy your stock from a breeder who strictly follows these procedures. We have followed a quarantine procedure even more strict than this for 30 years—and have remained disease-free, guaranteed. It is for this reason that we are one of the few—if not only—remaining places to purchase safe, healthy stock.

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