It is not required if you are keeping freshwater fish because those fish are better suited to captivity. Freshwater fish sold as pets are normally raised in a tank and are not prone to infections. Even so, if a fish falls sick you will need a quarantine tank.

For those people who keep saltwater fish a quarantine tank is a must. Saltwater fish are caught in the wild and are not used to tanks. This puts them under a lot of stress (yes, fish can feel stress too). A fish under stress is more likely to catch a disease than a happy fish.

A quarantine tank isn't really a jazzy affair. It can be a simply ten or twenty gallon aquarium. Of course, it depends on the size of the fish. The quarantine tank doesn't need all the bells and whistles that you have in the main fish tank.

A typical quarantine tank would have the following items:

* A filtration unit. Use the quarantine tank filter without the carbon because carbon usually removes whatever medication you might add to the water.
* Heater. This is to control the water temperature.
* Powerhead. You may also use an airstone to keep the surface agitation high.
* Test kits to check the pH, ammonia, nitrite, and nitrate properties of water.

Just turn on everything in the quarantine tank after filling it with water and then add the fish from the main tank.

Newly acquired fish need acclimatization to the water in the quarantine tank. Monitor them closely for about two or three weeks for parasites and bacterial infections. Should there be any evidence of such a problem then use appropriate medicine and continue quarantine for a couple of more weeks. Once you are sure all problems have been solved the fish can be transferred to the main tank for acclimatization.

If a fish falls sick in the main tank then take it out using the net and place them in the quarantine tank. At this point acclimatization is not required as the fish are already used to tank water. No matter how fast the fish heals, it is important to keep them for an additional week in the quarantine tank under observation.

In case of saltwater quarantine it is important to always keep some saltwater handy for emergencies. All water parameters must be monitored on a daily basis (or at least once in two days unless you want the fish to spend a lot of time in quarantine). Do not add freshly mixed saltwater into the tank as it is very toxic.

While freshwater fish keepers can do without a quarantine tank it is a definite necessity for people who wish to keep saltwater fish.