Quarantining New Marine Aquarium Fish

Do I need to quarantine new saltwater fish arrivals to my aquarium?

Are quarantine tanks essential or just a waste of time?

Should I set up a quarantine tank for fresh aquarium fish, or will it just cause more headaches?

Most experienced aquarists agree that the practice of quarantining new fish before they are released into the main aquarium is one of the fundamental keys to success, especially where reef aquariums are concerned.

While I recommend quarantining both new freshwater and saltwater fish, the practice becomes crucial on the saltwater side of the hobby for several reasons. While quarantine tanks take some time to set up, they do not have to be elaborate or expensive. A good and reliable quarantine tank can be set up relatively cheaply and doesn’t require much effort once it is established.

Many of the saltwater fish we keep in aquariums come from the ocean. While captive breeding programs show promise, many ornamental fish species can only be acquired through wild capture. The problem with this is that saltwater fish caught from the wild already have a minor parasitic infection controlled by the fish’s natural immune system. Once removed from their environment, shipped across the world, and placed in the aquarium setting, the once-dormant parasitic infection, such as marine ich, can reappear full blast.

The stress of capture and shipping is often enough to suppress a tropical fish’s immune system and allow any parasite (not to mention those it may have picked up in the dealer’s tank) to gain a strong foothold. Quarantining new tropical fish is essential. While the tropical fish may appear healthy in the dealer’s tank and even in your tank for several days, that parasitic or bacterial infection it harbors can then attack your entire aquarium within weeks.

In the ocean, parasites are kept under control naturally. However, because aquariums are closed systems, they can promote severe parasitic or bacterial outbreaks that wipe out entire tanks full of gorgeous and expensive aquarium fish and other animals. In reef aquariums, treating outbreaks once they appear is difficult, if not impossible, because many chemical and environmental treatments kill sensitive corals and invertebrates. Quarantining new aquarium fish is the best course of action for parasites and bacterial infections in the saltwater aquarium hobby.

The only time I recommend not quarantining new fish is if your local fish store is willing to do it for you. I know several local fish stores that will quarantine fish for up to two weeks if the tropical fish is paid for in advance. While this is better than no quarantine time, I feel two weeks is a short period for saltwater fish. When quarantining new tropical fish, I had had the best success when I quarantined the fish for up to two months in a quarantine tank before releasing them into the main aquarium. While this may sound like a dramatically long time, many saltwater parasites have intricate life cycles and can be tough to diagnose and treat quickly.

One thing to keep in mind while quarantining new tropical fish is that it does not only serve to protect your main aquarium’s fish from parasites or treat your new saltwater fish for an existing infection. Quarantining new fish in a quarantine tank also gives a new tropical fish time to relax and adjust to life in aquariums without the added stress of getting used to a new set of tankmates.

I often find it much easier to get tough-to-feed fish to eat in quarantine, and I can get the tropical fish in better health before I transmit the fish over to the display aquarium. Also, having the tropical fish in confines allows the aquarist to experiment with feeding to learn just what fish foods or combinations of foods work best for the individual species.

Overall, quarantining new saltwater fish is one of the fundamental building blocks to success with saltwater aquariums. While they aren’t fun to set up, tanks used for quarantining new tropical fish represent an essential tool in the hobby and have been used by many aquarists over the years.


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