Quarantine tanks are often discussed/written about as though they require very little effort, planning, or expense. Just dust off that 10-gallon plastic “critter keeper” sitting on the shelf, fill it with salt water, drop in a heater and sponge filter, and you’re good to go, right? Unfortunately, it’s not really that simple.
One could argue that in their justifiable zeal to encourage marine aquarium hobbyists to quarantine all their livestock, some aquarium authors (myself included, admittedly) and others with a voice in the hobby have created some false impressions about the practice. Here are a few of the quarantine tank myths I’ve noted over the years—and probably even perpetuated to some degree:
1. A 10-gallon tank will do ya!
This may be true for very small species, but many of the specimens swimming in the sales tanks at your LFS will be significantly stressed if crammed into such a small system for a minimum of four weeks (potentially even longer if disease treatment is necessary). I’ve found that a standard 29-gallon tank—which, let’s face it, will cost significantly more than that plastic keeper with the slotted lid—works pretty well for most of the specimens available in the trade.
It’s also important to remember that, just as with small display tanks, small quarantine tanks are less stable than larger ones with respect to water quality, chemistry, and temperature, which can add stress on top of stress for newly acquired specimens.
2. No substrate is necessary
Again, this is often the case, but not always. Burrowing or burying species, such as jawfishes, shrimp gobies, and various wrasses, often find the absence of substrate highly disconcerting. In fact, I once had a newly quarantined Wheeler’s shrimp goby (Amblyeleotris wheeleri) repeatedly slam itself against the glass bottom of the tank in an effort to reach anything resembling the ocean floor.
That doesn’t necessarily mean you need to have substrate covering the entire bottom of your quarantine tank. Oftentimes, fishes that burrow or bury themselves will be content with a tray filled with substrate material. Some may even do okay with sections of PVC pipe to hide in, but be ready to add at least a tray of substrate if PVC “caves” don’t cut it.
3. You don’t need lighting either
I would amend this to say you don’t need dedicated lighting for a quarantine tank. You do, however, need the ability to observe quarantined specimens clearly for signs of disease, and that’s kind of difficult under ambient lighting.
When I have a fish in quarantine, I don’t keep a light fixture permanently in place over the tank. Instead, once a day, I briefly transfer one of the LED fixtures from my adjacent 125-gallon FOWLR tank to the quarantine tank so I can give the specimen a good “once over,” then I move it back to the display tank. This process can be a bit of a hassle, but it doesn’t cost me anything.
4. Quarantine tanks are just for disease prevention
If you’re acquiring a specimen that you’re fairly confident isn’t diseased (e.g., from a trusted fellow hobbyist), you may be tempted to skip the quarantine stage because there’s no point to it. But remember, the quarantine period isn’t just a time to observe or treat for disease. It’s also an opportunity for new specimens to recover from transfer as well as get accustomed to your particular water conditions and the foods they will be offered before they have to compete with tankmates in a display system.
5. Biofiltration is unimportant
Advising hobbyists that a quarantine tank can be set up only when needed and taken down afterward may create the false impression that it doesn’t need to have a mature biofilter in place. Just as with a display aquarium, a quarantine tank must have biofiltration in place to convert deadly ammonia to less harmful compounds before it can safely hold any livestock.
Because quarantine systems tend to be temporary setups, biofiltration is usually provided by either borrowing live rocks from an established system or by using a sponge filter or other type of biofilter that has been operating on an established aquarium (in addition to the system’s primary filtration) and is, thus, already inoculated with beneficial nitrifying bacteria.