Aquarium hobbyists rely on healthy populations of nitrifying bacteria, clean up crews, microfauna, algae, fish, coral, and many other diverse lifeforms to process waste in their aquariums. It can take half a year or more for these populations to mature and stabilize, even with the help of pre-seeded media, live rock, and bottled bacteria. It takes time. We all know that a quarantine tank is the best way to introduce a new fish to your home, but how is anyone supposed to keep a quarantine tank from crashing without all the diversity in a mature system?
The secret aquaculturists know is that organic matter left in the tank for any amount of time can turn deadly very quickly. It’s important to constantly remove waste from immature tanks. Failing to do so can cause acute ammonia spikes, ORP drops, pH swings, infectious bacteria growth, acute oxygen depletion, and other issues that may not be easily diagnosed or requires special equipment to test that hobbyists don’t have immediate access to.
In addition to your regular maintenance, we strongly recommend siphoning the quarantine tank before and one hour after each feeding. Thoroughly remove all detritus, feces, and uneaten food. Pay special attention to anywhere detritus can collect, like under rocks or hides. You will need to use a scrub pad to scrub the bottom of the tank as needed. Also frequently squeeze and rinse mechanical filtration like sponges in the tank water you removed during water changes, since organic matter can collect there quickly. Organic matter left in an aquarium starts to decay and attract bacteria almost immediately.
Even in quarantine aquariums that have "cycled" media or rock, the diversity, stability, and overall maturity is still lacking. This can cause temporary but deadly ammonia spikes that may not even register on an ammonia test because the bacterial action processed the ammonia quickly. Keep an ammonia badge in the tank to help alert you to ammonia spikes, but also be aware that having “cycled” media or rock in your temporary tank does not mean your tank is safe from ammonia spikes.
You may be thinking, "This sounds a bit unnecessary. I always do one larger water change each day on my quarantine, and that has worked for me." Keep in mind, though, some fish are more hardy than others. Removing waste frequently is particularly important for more sensitive species like Regal or Multibar Angelfish, for example, that have a hard time tolerating swinging parameters and immature aquariums. If you're an advanced aquarist and an expert on the species you're quarantining, you might be able to avoid siphoning as often if you can keep meals small and make sure the food is eaten quickly, but this is a difficult balance even for experts.
We recommend feeding 3 - 4 x a day when fish are young or newly introduced. Keep feedings small, but frequent. If the fish isn’t eating at all, keep the portions tiny. You’ll want to give the fish enough time to notice and eat the food, but don’t leave the uneaten food in the tank for too long.
Some fish are more tolerant to water quality issues than others. Fish that have just been shipped and also sensitive species are sort of like "canaries in the coalmine," so they'll often be the first to show symptoms of water quality issues while other fish seem OK. Having one fish in the tank that is struggling while the others look healthy does not indicate good water quality, and it doesn’t mean the struggling fish is defective in some way.
It’s extremely important to make cleaning and siphoning part of your feeding regimen. It can sound tedious to have to siphon and clean the tank so often to prevent these issues, but it only takes a few minutes each time to quickly siphon the tank bottom and scrub it with an algae pad as needed. You don’t need to remove a large volume of water around feeding times, just enough to remove the waste. Keep a small bucket and a thin siphon hose next to the quarantine so you can quickly and easily perform the needed maintenance. Also keep a large container with mixed saltwater on hand at all times so you’ll always have pre-made water on hand when you need it.
An Acclimation Box is a Great Tool for EVERY Aquarium
If you can’t use a quarantine aquarium, an acrylic acclimation box can serve a similar purpose - conditioning new fish and letting them interact with your existing fish in safety. Even if you quarantine your new fish in a separate aquarium, we still recommend using an acclimation box when you move the new fish into the display.
How to introduce new fish to a tank that already has fish
We strongly recommend introducing any new fish to a tank using an acclimation box; this is particularly important for smaller fish. This allows the fish to get to know each other. More importantly, using an acclimation box also lets you keep a close eye on the fish so you know it is getting food and isn't swept away by pumps or filtration while it's tired from its long journey. Make sure your acclimation box is large enough to accommodate your new fish comfortably for several weeks. Place it in an area that gets plenty of flow so the water inside doesn't become stagnant. Provide lightweight hiding places like PVC or macroalgae in the box. Observe the fish in the box for at least a week, and if the fish aren't acting aggressively toward it, try releasing the fish. If the fish fight, ideally you'd catch the aggressor and isolate it in the acclimation box to allow the new fish to get used to the tank. If you can't catch the aggressor, it's OK to put the new fish back into the acclimation box until signs of aggression are gone. With particularly aggressive fish, you may need to repeat these steps.
Why do I need a quarantine aquarium?
A quarantine aquarium isolates your new arrivals and gives them a chance to regain strength before going into the display tank with other fish they’ll have to compete with for territory and food.
Although our marine biologists practice strict biosecurity at our facility, we still recommend all aquarists use a quarantine and conditioning aquarium as good practice. We should all do our best to provide the best conditions for our pets, but it’s not possible to have complete complete control over all the lifeforms in our aquariums, including the ones we don’t want.
There’s a scene in Jurassic Park in which Jeff Goldblum’s character warns the scientists that they can’t expect to control the dinosaurs, and we think it’s a great metaphor for our captive aquarium environments. -
Dr. Ian Malcolm : “John, the kind of control you're attempting simply is not possible. If there is one thing the history of evolution has taught us it's that life will not be contained. Life breaks free, it expands to new territories and crashes through barriers, painfully, maybe even dangerously…I'm simply saying that life, uh... finds a way.”
How to set up a quarantine tank
Dos and Don’ts of Quarantine
Though proper quarantine is an excellent practice, we don't recommend using medications prophylactically on very young or newly shipped fish. Please give your fish plenty of time to grow and condition them well if you plan to use any preventative medications.