Introducing new fish

Introducing new fish


By Jim E. Quarles

This subject is one that every new hobbyist should know by heart and even the breeders that have been in the hobby for a while should review the rules of the game.

You might be surprised at how many times people who buy new fish and take them home don't know how to properly install them in a tank. It is not that hard to learn, and it will save you lots of heartache and even some money.

If you have a tank already in operation that is in good health and has proper water parameters you should never, repeat NEVER just dump new arrivals in the tank. Even if you use the proper procedures to release them like allowing the temperatures to adjust or exchanging a little water to adjust the ph.

I am amazed at the number of people who should know better that just release new fish into the established tank without quarantining them first.

The process of quarantining new arrivals is so fundamental and yet is so ignored thousands of fish are made sick or die along with costing huge amounts of money to treat diseases that could have been easily avoided.


Even if you see a fish you truly want to add to your collection you must assume for safety sake that it has diseases or at least is carrying some parasite or bacterial infection that will cause illness in your established tank.

By first installing a new arrival in a properly operated quarantine tank you can insure that this event does not happen. The amount of time required for a new fish to remain in quarantine will depend upon the fish and your good judgment. But a good rule of thumb is about two to three weeks.


There are a few simple rules that must be followed in making sure that the procedures are correct and successful for both you and the fish. The number one rule is that the tank has to be the proper size to meet the requirements of the new arrival. With discus fish a twenty to thirty-gallon tank works well. The second rule is that all equipment that will come into contact with the water or fish in this tank is used only repeat only in this tank. Nothing that comes into contact with a quarantine tank should ever be used in your established tanks, this means, nets, hoses, buckets that have contained water form the quarantine tank. The third rule is after handling anything required for the operation of this tank wash your hands and clean under your finger nails. You could be the carrier as well as a dirty net or hose so be careful about your procedures.

Needless to say but I will anyway, the water in your quarantine tank must be suitable to meet the requirements of the fish you intend to isolate. Make sure the water is the proper ph and that you have a working biological filter in operation in this tank. The temperature must be at the proper setting for the fish as well and don't forget the required water changes needed by all fish for good health.


Moving your fish out of quarantine can be tricky so you must be careful with this operation as well. If you do it wrong Ph. Shock and / or temperature shock can occur. There are several ways the transfer can be safely made. After the fish has been in quarantine for the time required you may be fairly sure it is not sick or a carrier of disease or parasites.

So now you can use two or three methods to move it to it's new home. One would be to bag the fish and float it in the receiving tank until the water temperatures are equal and while that is happening add some water from the receiving tank to the bag so that the pH can be also equalized. Then after about ten minutes you can simply net the fish out of the bag and place it in the tank. I would avoid discharging any water from the bag containing the fish into the receiving tank if possible. Remember use a clean net, not the quarantine tank net.

Another way to make the transfer is by the use of a small bucket, I often use this method. I simply take some water from the quarantine tank into the bucket and place the fish in the bucket with just enough water to cover it safely. Then I start an air tube siphon going through an air check valve into the bucket. You can adjust the rate of fill with the check valve.

I let the fish remain in the bucket for about twenty minutes and then simply net it into the receiving tank and dump the water out of the bucket.

Anytime you buy a new fish and add it directly to your main tanks containing other fish you are taking a very big chance of passing diseases or parasites to your established aquarium and this can be deadly and very costly. I keep a tank going that can act as a quarantine tank at all times it is easy to do, just keep a few guppies, swordtails or other fish in it to keep the biological filter going. Then when you need it is ready to be used.

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