Quarantine tanks are essentially auxiliary tanks that should be set up in accordance with the main aquarium. They are generally used to isolate sick fish or to observe new arrivals to minimize the initial stress of introduction or spread of disease. A 30-gallon tank is versatile and can make a great quarantine tank for both fresh and saltwater fish; a slightly larger or slightly smaller aquarium will often work just as well.
Setting up a quarantine tank is basically no different than setting up a “regular” aquarium. The main difference in set-up focuses mainly on equipment; in terms of a quarantine tank only the most basic equipment is necessary. Equipment included in this category is a filter, heater, thermometer, lighting system, and possibly an air pump. Since quarantine tanks are an extension of the main aquarium, specifications such as water temperature and pH should mimic the conditions of the water in the main aquarium. Quarantine tanks also need to be properly conditioned and cycled.
New arrivals to the primary aquarium should be isolated in a quarantine tank to help them recover from stress associated with transport and relocation; stress lowers the immune response of fish and allows disease causing organisms, which may be present in the main aquarium, to take advantage of their vulnerable condition. This also allows them to acclimate to new water conditions and they can also be monitored for health, making sure that they do not show signs of illness. Quarantining new arrivals is essential because even though they appear healthy, the new arrivals may not exhibit symptoms until days after purchase. Quarantine tanks allow new arrivals to regain their strength, making them more resistant to disease when introduced to the main aquarium.
New arrivals should be quarantined for at least 3 weeks; longer periods are preferable, however. Ich, a disease-causing organism, can take several weeks to complete their life cycle, making the visible signs possibly nonexistent for several days. The recommended extended quarantine period allows time to monitor signs of illness, which may include loss of appetite, color loss, wounds or sores and other physical or behavioral changes.
Isolating sick fish is the one of the most common purposes of a quarantine tank. They can also be used in emergency situations, such as a leaking tank. Since they are regularly cycled in with the main aquarium, they should be ready to accept any fish at any time.