Aquaponics bacteria

Fish waste (rich in ammonia) has to be broken down into something that is useful for plants and non-toxic to the fish. The aquaponics bacteria perform this crucial task and they do it well - as long as you get the aerobical bacteria. If your system grows anaerobic bacteria - you are in trouble. Keep your bacteria happy!

Did you know that, in an aquaponics system, there is more weight in microorganisms than in the fish? Absolutely amazing, isn't it. This can be especially hard to imagine in large commercial designs with hundreds or thousands of fish, but even there - the total mass of the aquaponics bacteria exceeds the total mass of the fish. And you absolutely need the good microorganisms for your setup to thrive. Few articles in our "aquaponics resources" section are as relevant to a thriving setup as this article on "aquaponics bacteria".

Why do you need these microorganisms?

The microorganisms are an often overlooked, but critical, component of a successful aquaponics setup. These bacteria will break down the fish waste, which is rich in Ammonia, into Nitrites and then other microorganisms will break that down into Nitrates. Ammonia and Nitrites are actually poisonous for the fish, and the plants can't consume Ammonia or Nitrites directly. So in an aquaponics system that has a poor microorganism population, both the fish and the plants will probably die.

Introducing microorganisms

There is no need to try to get the microorganisms into the system. The microorganisms are already everywhere around us. (Tip - if you are interested in kickstarting your system, see the article on "Starting Aquaponics" in the "Aquaponics Resources" section of this site). They are in the air, even though we cannot see them. They will naturally come into the plant bed, and when they find a rich feeding ground for them (ie, high in Ammonia or Nitrites), they will increase rapidly in quantity. Some people buy these microorganisms online, and while this may speed things up, it is probably a waste of good money - but hey, I'm happy to sell you some). The microorganism population will increase until there is a natural balance between the amount of Ammonia produced by the fish and the number of bacteria that thrive on Ammonia. It will take about 6 months for the aquaponics bacteria to become balanced in the system, and when it is balanced the aquaponics system works really well.

Initial nitrification cycle

When starting a system from scratch, there are obviously not the required quantities of microorganisms (good bacteria). The introduction of these microorganisms happens automatically. It takes about 30 days to stabilize, but not all microorganisms will be introduced into the system at the same time.
  • Ammonia starts building up slowly as soon as you introduce fish. This level will increase for approximately 10-12 days, and then it will decline to an acceptable level in approximately 5 days. This reduction is caused by aquaponics bacteria breaking down the Ammonia into Nitrites.
  • These Ammonia-eating bacteria start to develop about 10 days into the system lifecycle. The Nitrites that they produce start to build up. The maximum is reached after approximately 15 days (which is 25 days after starting). After about 5 days (15 days since the start), bacteria that transform Nitrites into Nitrates also start to build.
  • The bacteria that transform Nitrites into Nitrates have removed most Nitrites at day 40 after starting the system. At this point, there should be a lot of Nitrate, and little Ammonia or Nitrite.
If you are interested in learning more about this cycle, reference the "Nitrogen cycle" article that is in the "Aquaponics resources" section of this website.

Keeping the aquaponics bacteria happy

The microorganisms that you want, the good bacteria, are aerobic bacteria. Aerobic means that the microorganisms require air to live and thrive. There are also anaerobic bacteria, they thrive in locations where there is little or no air. Put simply: anaerobic bacteria make your system smell bad and will kill he fish. Aerobic bacteria don't smell, and make your system thrive.