Completing a fishless cycle on your tank is an amazing way to create a safe environment for your fish, while making sure that none are harmed in the process.


  • Tank and equipment
    • For a list of equipment needed for a basic betta tank, see our NECESSARY SUPPLIES page
    • Note that the smaller the tank, the harder it may be to cycle. Tanks of less than 5 gallons may prove difficult. Just another reason to choose a larger space for your betta!
  • Mechanical and biological filter media
    • For a discussion of the different types of filter media, see our FILTRATION page
  • Pure ammonia
    • This can be found in the cleaning section of most grocery or hardware stores
    • Make sure that the ammonia does not contain added fragrance or cleaners - these chemicals would kill fish and your cycle
      • Make sure that the only ingredients are water and ammonium hydroxide (ammonia)
  • Test kits
    • Ammonia
    • Nitrite
    • Nitrate
    • pH


1.   Rinse tank, equipment and decor thoroughly in tap water, then assemble, fill the tank with water and add water conditioner as directed. Plug in equipment and ensure that it is working properly.

  • Do NOT clean tank, equipment or decor with soap or another cleanser. This is very dangerous to your future fish. Only rinse with clean water

NOTE: even though there are no fish in the tank, it is essential to add water conditioner. Cholorine and chloramines are added to tap water to kill bacteria - including the type you are trying to grow - and they need to be neutralized.

  • If your water conditioner "neutralizes" or "locks" ammonia, this is fine.  This is an effect that wears off after approx. 24 hours, and so will not disrupt your cycle.

Add ammonia to the tank sufficient to bring the concentration to anywhere from 3PPM-5PPM.

  EXAMPLE: For a 10 gallon tank, start by adding only 2 teaspoons of ammonia. Wait an hour to allow the running filter to circulate the ammonia, then test.
  • If you have no measurable ammonia at this point, or your reading is below the desired level, add a little more ammonia, wait, then re-test.
  • Continue in this way until your ammonia reading is within the desired range, then stop adding ammonia
  • If you would like to use a "bottled bacteria" product, such as Cycle or Stability, this would be the time to add it
    • Note that these bacteria are bottled in a non-toxic form of ammonia (No4 - see our WATER CHEMISTRY page for explanation) but this may increase your total ammonia reading all the same

TIP: Test kit result colors can be difficult to distinguish dependent on available lighting, and should be read in bright white light. When in doubt, a flash photo with a digital camera may help you to determine.

This level of ammonia would be fatal to fish. Luckily, we don't have any in the tank!

3. Now you wait and allow the ammonia-consuming bacterial colony to develop. Monitor their progress through water testing.
  • Test ammonia daily, or once every other day. Your ammonia level may remain steady for quite a few days, which is fine.
  • When your ammonia level begins to drop, test for nitrates
4. When your ammonia reading has dropped to 0 or near 0, begin adding a small amount of ammonia daily to feed your newly developed bacterial colony
  • EXAMPLE: for a 10 gallon tank, 1 teaspoon/day should be sufficient.
    • You do not need to force an ammonia reading above 0 again, you simply need to feed your newly developed bacterial colony
    • You are now simulating the daily waste output of your future fish 
  • Regular testing, as outlined in step 3, is important so that the ammonia level does not reach and stay at 0 for any length of time, or else your newly grown bacteria may die off from starvation.
5. Continue testing ammonia and nitrites regularly. You will notice the nitrites spike (rise to a maximum) and then begin dropping. When they begin dropping, nitrates should be detectable
  • When your nitrites begin dropping, your cycle is almost complete!
6. When your ammonia and your nitrites reach zero (and you should have a significant amount of nitrates) your cycle has completed!
7. Perform a large water change (50-80%), replacing with fresh, conditioned water
  • Make sure to add water conditioner to your water change water BEFORE adding it to your tank. 
    • Otherwise, your new nitrifying bacteria will be exposed to, and killed by, the chlorine and chloramine in the tap water
  • This water change serves several purposes:
    • Lowering the (now high) level of nitrates accumulated in the water
    • Replenishing buffering capacity (KH) used up via exposure to acidic byproducts of the cycle (see WATER CHEMISTRY and pH CRASH for more on this)
    • Restoring pH to its baseline level, if it has been lowered during the cycling process (again, see WATER CHEMISTRY and pH CRASH for more)