Why You’re Doing It WRONG: 10 Misconceptions About Quarantining Saltwater Aquarium Fish!
1. Quarantine is NOT 100% foolproof
Quarantine is not a guarantee that your fish are entirely free of disease-causing bacteria, viruses, and parasites. While a good quarantine protocol can be as much as 99% effective at reducing infections and disease, there is still a chance that something makes its way into your display aquarium no matter how meticulous you are during QT. Yes, 1% is a pretty small risk, just don't get caught thinking it could NEVER happen to your fish because you follow a strict quarantine protocol.
2. Proper quarantine is NOT difficult
Quarantine takes some effort but is not really complex or difficult. As long as you have the gear and follow the steps, you can eliminate a majority of the most common threats. Don't fall victim to the rumor mill about quarantine being difficult and not practical for average hobbyists.
3. Fish that have been quarantined can still get sick
A fish that has previously been quarantined does not become immune to pathogens or repeat infections. If a pathogen exists in your display aquarium, even a QT fish is at risk of infection. In some cases, fish that are fresh out of quarantine have a suppressed immune system due to the stress and medications in the QT process which means they are actually at a higher risk of infection upon being introduced into a display.
4. Copper doesn't kill ALL parasites
While copper is an effective treatment against protozoan parasites like ich and velvet, it will not be effective against flukes, brooklynella, or uronema. Short of it, there is no "Cure-All" fish medication that will effectively treat ALL of the possible pathogens. Prophylactically medicate for the most common pathogens and if you need to target something specific, be sure to research and find the most effective medication for that specific ailment.
5. After an outbreak of disease, a fallow period is required to avoid repeat infections
If you pull fish from your display tank for treatment of a known disease, it is important to eliminate those pathogens from your display tank before reintroducing the fish after treatment. Even if you treat fish with medications in a separate quarantine tank, they are still susceptible to reinfection if the pathogens or parasites exist in your display. The typical protocol is allowing the display tank to run fallow for 72 or more days without any fish. Yes, that means even fish that don't display symptoms of illness will need to be removed from the display. It should also be noted that if a fish in your display is showing signs of illness, the pathogen or parasite causing these symptoms is most definitely in the water or substrate and will remain in the water or substrate even after removing the affected fish.
6. Other animals (and corals) can carry fish parasites too
Parasites, bacteria, and viruses can hitch a ride on corals and invertebrates, even if they are not directly infected. Once a pathogen is in your tank, your fish are now at risk even if they have been previously quarantined. Some pathogens can even be aerosolized and migrate through the air to infect your display. This is why it is important to always perform your quarantine at least 10ft away from your display; a separate room is better.
7. Quarantine isn't always necessary
There are some fish that don't do very well in medications and pose a lower risk of introducing pathogens (such as Mandarin Dragonettes). Furthermore, if you have not quarantined ALL of the fish in your display tank there is a good chance pathogens exist. In this case, you will do your best to manage the risk of infection with UV sterilizers, good water quality, and optimal nutrition. The act of quarantining any new fish while practicing a "management" style of disease control will still not eliminate the risk in your display.
8. Sick fish will NOT always do better in a display aquarium
If a fish is showing signs of illness, it will very rarely have a better chance of surviving when placed directly into your display over following a quarantine protocol. While quarantine is stressful, the illness is still a threat when a fish is placed in your display and it will put your other fish at risk. Going through a quarantine protocol is a better choice 99% of the time.
9. Most medications will not kill your biological filtration
There is a widespread belief that fish medications will kill beneficial bacteria. This is simply not true. Most common medications such as copper, formalin, and even antibiotic-based medications are generally safe for nitrifying bacteria. Don't let this rumor convince you that quarantine is a hassle.
10. 100% water changes are required
Small water changes during quarantine simply won't cut it. With a proper quarantine protocol, it's very important to perform 100% water changes and completely clean the QT tank in between water changes so as not to transfer disease-causing pathogens.