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One of the hidden trials of aquarium keeping is mastering the mysterious nitrogen cycle. If you toss fish into an uncycled tank, they’ll be fine for a while, before the ammonia created by their own waste overwhelms them.
Lucky for us, the nitrogen cycle, and the nitrifying bacteria it comprises, absorb that ammonia, making the water safe. But what if the source of ammonia disappears? How long can nitrifying bacteria live without ammonia?
Nitrifying bacteria can survive 1 to 2 days without ammonia, but after that, they start to die off. After a week without ammonia, most nitrifying bacteria in a tank will be gone.
Can Nitrifying Bacteria Survive Without Ammonia?
Nitrifying bacteria need ammonia to survive, so when no ammonia is present, they will die off.
That being said, there is a big difference between adding nitrifying bacteria to an empty tank full of water and nitrifying bacteria living in a tank that previously had livestock in it but is now empty.
In a tank of just water, there will be 0 ammonia for the bacteria to subsist on, but in a tank that was previously occupied, there will be decomposing bits of food, plant matter, and waste that will supply ammonia for a short period of time.
So if you have an empty tank that was just recently full of fish, you have a little more wiggle room to work with with the time frame of nitrifying bacteria dying off.
What Are Nitrifying Bacteria?
Nitrifying bacteria process dissolved nitrogenous waste products excreted by the aquatic organisms being cultured. All life in an aquarium produces waste, and this waste turns into ammonia as it decomposes.
First, the nitrifying bacteria break down the ammonia created by the waste, turning it into nitrites. Nitrites and ammonia are both very toxic to fish, so even a small amount of either one in a tank can cause issues.
At this point, more bacteria will break down the nitrites, turning them into nitrates, which can be tolerated by fish at much higher levels than either ammonia or nitrites.
This process is known as the nitrogen cycle.
Does Nitrifying Bacteria Need Ammonia?
Nitrifying bacteria need ammonia to survive and thrive, but livestock in the tank isn’t the only way to supply ammonia.
Cycling a tank with fish in it is dangerous to the fish, which is why a fishless cycle is a preferred method of preparing a tank. But how can you cycle a tank with no creatures to provide ammonia?
Bottled ammonia can be used to feed nitrifying bacteria when a tank is undergoing a fishless cycle.
Even though nitrifying bacteria can’t live without ammonia, don’t stress about not having any fish in your tank just yet. Cycling with bottled ammonia is a safer alternative to fish-in cycling.
If you don’t have livestock or bottled ammonia, some aquarium owners have had success using a process called ghost-feeding to produce ammonia.
Ghost feeding consists of sprinkling small amounts of fish flake into the uncycled aquarium. The decomposition of these flakes will produce ammonia, kick-starting the nitrogen cycle. Be advised, ghost-feeding is a lengthy process.
How Long Do Nitrifying Bacteria Live?
Most nitrifying bacteria live for a few days but replicate rapidly.
There are some reports from experts that nitrifying bacteria can become dormant and live for much longer in certain conditions, but this isn’t something that can be replicated in a home tank.
Can Nitrifying Bacteria Starve?
Like any living thing, nitrifying bacteria need certain things to survive, sustenance included. Yes, nitrifying bacteria can starve.
The good news is that in a fully cycled tank, the number of nitrifying bacteria present should be enough that, even if a good portion dies off, the population can bounce back. Nitrifying bacteria replicate quickly enough that as long as some are left behind, a tank shouldn’t fully crash.
If you know that your tank will be without an ammonia source for any significant amount of time, consider using bottled ammonia to keep your bacteria fed and plentiful.
What is nitrification?
Nitrification is the process of establishing a bacterial colony that absorbs ammonia, turning it into nitrites, and then absorbing nitrites, turning them into the much-less-harmful nitrates.
Can nitrifying bacteria live without water?
Nitrifying bacteria don’t live exclusively in aquatic environments. We can find them in other moist areas as well, like soil.
Do aquarium bacteria starters work?
Yes. Aquarium bacteria starters can speed up the cycling process, but there is no substitute for filter material from an already cycled tank for kick-starting a new tank.
How soon do nitrifying bacteria start to die off?
Nitrifying bacteria start to die off within 24 hours, but a cycled aquarium should retain some amount of nitrifying bacteria for anywhere from 1 day to a week.