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I have been considering this article for some time, but have avoided it intentionally. The reason is simple. All experienced hobbyists agree that the use of a quarantine (Q) tank is necessary for successful saltwater aquariums. This is not up for debate. What we have a hard time agreeing on are the details of exactly how to go about using the Q. If you follow recent literature, you will find disagreements from the experts in our field on every aspect of Q care, ranging from length of Q period to correct specific gravity levels.

In this article I am not attempting to disagree with other methods of quarantine. What I am offering you is this. I have been keeping marines for nearly 20 years. What you will find here is how I personally go about the Q process for my livestock purchases. There is your disclosure, so lets get started.

I see the benefits of a Q as this. Fish arrive at the LFS very stressed, due to collection, shipping, and handling. They often have a weakened immunity and need a place to relax and grow strong prior to being introduced into the display tank. Fish also are prone to showing signs of disease for 3 to 4 weeks following purchase. Often this disease is not visible at the LFS. Keeping all newly purchased fish in Q allows the fish the best chance to regain its strength, and allows you to observe the fish for disease, protecting your display from infection.

For the Q, you want a minimum of a 10 gallon tank, but may need something larger if you are purchasing larger fish. (For my 180 gallon tank I use a 38 gallon Q.) When thinking about Q filtration I am not worried about Nitrate buildup. The Q will have a lot of water changes, and Nitrate buildup is not an issue. ( More on this later.) For filtration, you probably have an old hang on filter from a freshwater tank that would suffice. The AquaClear hang on filters are ideal, using the sponge filter for a biological filter to break down ammonia and nitrite.
You can also use a very simple internal sponge filter, often seen in breeder tanks:

Each of the filters above provide an excellent place for bacteria to colonize and break down waste. I personally like sponge filters because the sponge can be "seeded" by the display tank. When you set up your display, simply take the sponge and place it behind your live rock structure. Give it a few weeks and the sponge will be biologically active. Place it back into the filter on your Q, and you have an effective filter for the Q tank.

A Q tank can be an empty aquarium, with a sponge filter, heater, and large piece of PVC to serve as a cave for the fish to hide in. I generally keep my Q specific gravity at 1.016. When bringing a fish home, I allow the water in the bag to rise to room temperature, and then I add the fish directly to my Q, which is kept at 76F. I do not acclimate to the specific gravity. I believe this quick drop in specific gravity to be effective at causing stress to any unseen parasites which might be present on the body of the fish. I have handled literally hundreds of fish using this technique, and have never had any issues. This is similar to a "dip", which is believed to cause parasites to die but causes no long term problems with the fish. (For the record, I acclimate invertebrates with great care, using a drip method, adding them to my display without Q.)

I leave the Q at 1.016 for 2 weeks, observing the fish closely. The fish need a very consistent routine during this period. You should "trigger" feeding time by turning on a light in the room, or having some other trigger that the fish associates with feeding. It may take a few days for newly purchased fish to feed. I don't worry about it. I also do not stand around watching the fish feed. A new fish is very shy, and prefers to be left alone to feed at its leisure. I generally wait a week or so, until the fish associates the trigger and my presence with feeding, before I begin to observe the fish feed.

During this time I also monitor ammonia and alkalinity closely. Testing for ammonia 2 times per day for the first few days after adding a new fish is important, just to insure the biofilter is doing what is expected. Alkalinity testing needs to be monitored closely as well, testing 2 or 3 times weekly, especially with a lower specific gravity.

After 2 weeks, if all is well, I begin to raise the specific gravity with a series of water changes. I generally change 10% per day until the specific gravity reaches 1.024, matching the display. After 3 weeks if the fish is healthy and eating well, I move it to the display, again with no acclimation. The water in my Q and display have the same temperature and same specific gravity.

Before my next purchase I do several 5 gallon water changes to bring the specific gravity back down to 1.016. You do this by removing saltwater, and replacing it with freshwater, which lowers the specific gravity.

This is my technique, and I have found it to work very well. You will notice that I do not treat for internal or external parasites in the Q tank. I do not believe in preventative treatment using chemicals. I find the lower specific gravity to be all I need for a successful Q period, along with the feeding of garlic enhanced foods.

Realize, there will always be situations in which a fish dies in Q. This is just part of the risk of our hobby. Fish are captured from the depths of the ocean, brought to the surface, transported, held in holding facilities, bagged and shipped to a wholesaler, held again for a few days, bagged and shipped again to a distributor, then ordered by an LFS, bagged and shipped again, and then placed into a brightly light tank at the LFS for offering to the public. Given the level of stress these fish endure, it is not a surprise that fatalities occur. (This is a great reason to buy captive raised fish!)

Our job with Q is to allow the fish the best opportunity for acclimation to captive life, decreasing the fatality rate tremendously,

This is my technique. There are other effective techniques as well. As always, if you have questions feel free to ask.

Thanks for reading & Happy Fishkeeping!
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