Sunday, February 25th, 2018

Fishless Cycling – Cycle Your Tank with Fish Food or Ammonia


In this post we look at an alternative to the typical method of cycling your fish tank with fish.  Called Fishless Cycling, it is a method of starting the Nitrogen cycle with something other than fish.

All that is needed to start the Nitrogen Cycle and begin the building of beneficial nitrifying bacteria is ammonia.  Ammonia is created in your aquarium by fish waste – rotting plant leaves, excreted waste from your fish and uneaten fish food to name a few sources.  While the standard method to start the cycling process has been to introduce a few hardy freshwater or saltwater fish into your aquarium, the cycling process can be hard on these fish, and these may not be fish you want to keep once your tank is ready to go.

Fishless Cycling with Fish Food
Decomposing fish food is an inexpensive (and more humane) method to introduce ammonia into the aquarium.  Any type of fish food works well to kick off the process – flake food, pellet food, or even chopped up shrimp (frozen or raw).

To start cycling your tank with fish food, you want to make sure that your aquarium is fully setup with your filter equipment operational.  The objective of the cycling process is to establish sufficient numbers of beneficial bacteria to process both the toxic ammonia and nitrites that are produced in a tank into the less harmful nitrate.  Without your filter equipment running during the cycling process, there may not be sufficient surface area for the bacteria to grow on to deal with the increased levels of ammonia and nitrites produced when you add your fish.

Once your tank and filter are setup, simply add some fish food to the tank to get started.  If you are using pellet or flake food, start off with a measured teaspoon of the flakes on day 1, and then simply add a small pinch of food each day to keep a steady supply of organic matter in the tank to produce the required ammonia waste.   The decaying food will begin releasing ammonia, and the tank will start the cycling process.

If you don’t want to worry about “feeding the tank” on a daily basis, then you can chop up one or two tablespoons of raw or cooked shrimp and place it into the aquarium.  Follow the testing instructions listed in How to Cycle Your Fish Tank to determine when the cycling process has completed and your tank is ready for stocking with fish.

To keep cleanup of your tank easier through this process, place the food in an old sock (nylon is best!) which can be removed and thrown out once your aquarium has been fully cycled.

Fishless Cycling with Ammonia
Rather than using fish or fish food to produce ammonia and kick off the Nitrogen Cycle in your tank, why not go straight to the source?  You can cycle your tank with ammonia just as easily as using fish or fish food.  You can find ammonia at your grocery store, but want to make sure that you select pure ammonia – don’t get a brand with perfumes or added cleaners or surfactants as they can leave residue in your tank.

To start the Nitrogen Cycle with ammonia, begin by adding a teaspoon (tanks up to 20 gallons) or tablespoon (20+ gallon tanks) of ammonia to your aquarium.  Continue adding ammonia until you get a reading of around 5ppm (parts per million).  At this point you can stop adding ammonia to your tank.  In about 7 to 10 days, you will notice the ammonia levels drop suddenly, down to a level approaching zero.  The bacteria in your tank able to process ammonia into nitrites are now at a sufficient level, and your tank is now starting the second stage of the Nitrogen Cycle – growing the bacteria able to process the resulting nitrites into nitrates.  At this point, you want to begin adding a small amount of ammonia to your aquarium again to keep these bacteria fed, and to continue to produce nitrites for this part of the process.  Follow the testing instructions listed in How to Cycle Your Fish Tank to determine when the cycling process has completed and your tank is ready for stocking with fish.


4 Responses to “Fishless Cycling – Cycle Your Tank with Fish Food or Ammonia”
  1. Deborah DeRosa says:

    My 45 gal sprang a leak. We bought a 54 gal cornerback bow. Can I cycle the new tank with the old tank bioload? There is not enough water to fill the 54, as at least 12″ leaked out. But there is eight inches left. The fish are still in the leaked tank. Can I set up a 30 gal with all the material from the bad tank (substrate, canister filter, water and fish)? Is this sort of cycling too fast for the fish? Please advise


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