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Fishless cycling – start an aquarium without fish

The Classic Approach

When setting up an aquarium, buy some cheap, hardy fish and get the cycle started. These fish have been given names like starter fish, suicide fish, disposables, and so on.

The purpose of starter fish is to provide ammonia through respiration, fish waste, and decaying food. The ammonia allows the first set of nitrifying bacteria to colonize, and initiates the cycling of the tank.

During this time of cycling, ammonia and nitrites will spike up to dangerous levels for the fish. Some of them will survive the harsh welcome, but will not live out their full potential. There are always a few exceptions to this rule.

The cycle is complete as soon as ammonia and nitrite levels are no longer measurable by test kits. This classical form of cycling takes anywhere from thirty to forty-five days.

Using Fish Food to Cycle the Tank

Another form of cycling the aquarium is without fish. Set up the tank with all the equipment needed: filtration, heater, light, protein skimmer for marine and reef tanks, etc. Start it up, setting the heater to a temperature around 80° F, then simply feed the tank with fish food. The decaying food will release ammonia, and the tank will start the cycling process. To speed up this process, the tank can be seeded with supplies from established tanks, such as gravel, filter cartridges, filter media of any kind, biowheels, drift wood, and rocks.

Bacteria colonize all of the above, so seeding introduces existing bacteria colonies to a new tank. The decaying food will provide ammonia for these colonies to settle and expand in the new tank.

This fishless cycling method requires a similar amount of time as classical cycling. Also, the ammonia produced might be insufficient to create enough bacteria colonies to hold the fish when they are introduced. This will trigger another growth of bacteria with the spikes in ammonia and nitrites.

These renewed spikes, however, will be much shorter and less intense compared to the initial ones experienced during the primary cycle. Consequences for the fish are minimal, making this method more fish-friendly.

Both forms of cycling have one thing in common – Ammonia.

A tank has cycled if ammonia and nitrites are back at zero ppm. At this time, you can stock the tank with fish. If no fish are introduced, the bacteria will need to be fed by continuing with the addition of fish food or pure ammonia.

Using Pure Ammonia to Cycle the Aquarium

Instead of using fish food for ammonia production, you can introduce pure ammonia to the tank.

After the tank has been set up, add five drops of ammonia per ten gallons into the water on a daily basis.

Ammonia will rise to five ppm and higher. As soon as nitrites are measurable, reduce the ammonia input to three drops per day. Nitrites will rise to similar levels. Keep adding two to three drops until the measurements of ammonia and nitrites come out with zero ppm. The tank has then completely cycled.

Seeding the tank can significantly enhance this process. It is possible for a cycle to complete in seven days with seeding; otherwise this method takes two to three weeks.

The bacteria colonies produced using this method are large enough to handle a well-stocked aquarium.

Some aspects to consider

  • The tank has to be well oxygenated because the bacteria require oxygen.
  • The ammonia used should be free of any perfumes and additives.
  • Do not treat the water with conditioners that remove ammonia.

Water changes are only necessary if the ammonia and nitrite levels are far off level, which should only occur if more than five drops are used per ten gallons of water. After the cycle has been completed, use activated carbon to remove any possible perfumes or additives that might have been in the ammonia.

After stocking your tank with fish, general maintenance of the aquarium is all that is required. The bacteria will adjust to the fish load, and if you plan to add new fish, the bacteria will have to adjust again.

Remember to feed your tank with ammonia until you introduce fish. The waste generated by your fish will then provide the tank with all that is needed to balance the environment.

With the ammonia drop method, all aquarium types can be cycled in a very short period of time.

Professionals use this method to keep live sand and rock alive to sell in their stores.

We recommend you read about the nitrogen cycle so you have an understanding about what happens during this cycling period. You will also need ammonia, nitrite, and nitrate test kits to perform your daily testing of the water.

10 thoughts on “Fishless cycling – start an aquarium without fish

  1. 14 days ago i got a 29 gallon fish tank new from petco i had a 24 gallon that i got at a yard sale nothing but problems. when i got the 29 i put all the stuff that i had in it in the 29. this was the 21st of July 2016. my tap water has ammonia in it. tap water readings is ph 7.2 Ammonia 0.50 nitrita 0pmm nitrate 5.0 tested the tank on the 24th Ammonia was 0.25 the 25th was 0.50 26th was back to 0.25 today i tested the tank Aug 4th 2016 Ammonia still .25 nitrite 2.0 nitrate is 20pmm i am doing a fishless cycling. is my tank working on the cycle or am i at a stall.

    • It’s hard to say but it would seem you are at a stall. Normally ammonia spikes only last a couple of days when breaking in a new aquarium. Obviously it’s not ideal if your tap water contains ammonia to begin with either. You may want to try to add some drops of ammonia as outlined in this article as this may increase the number of nitrifying bacteria to the point of being more efficient in breaking down these nutrients.Just be careful to increase the ammonia in small increments while regular testing the water for its effects.

  2. Today is the second day of fishless cycling my 5 gal tank. I’m doing the fish food method and I’m using Aqueon Betta food pellets. The water is super cloudy and I read that that’s called “bacteria bloom” but I can’t find out if it’s good or how to fix it. I’ve noticed that a lot of people experience this on their fifth day of cycling, but it’s happening on my second day. Does it have anything to do with the amount of fish food I put in there? I put quite a bit, I couldn’t find an amount that you should do. I’m a beginner and I have a whole lot of conflicting information and I really don’t know what I’m doing.

    • You shouldn’t put too much food in the tank. Just a pinch, especially in a small 5 gallon tank. If the cloudy aquarium water is white in color, then it is indeed a bacterial bloom. Usually this will clear up on its own as the fish tank balances. You can also use Algone to help clear it up if the problem doesn’t resolve itself. Just take your time and be patient. You can’t rush a healthy aquarium and should always make small incremental changes moving forward.

  3. Im thinking about doing a 55gallon aquarium so for the cycling process I just introduce pure ammonia. To the tank instand of just using fish food I think I’ll just do the fishless cycling its much easier for me to do what stores might carrier pure ammonia.

    • You should be able to find it at a department store such as walmart or target in their cleaning supply section. Alternatively you local pet store may carry something for this very purpose.

  4. Using the fishless cycling method with fish food, how often do you add more fish food and what do you use as an indicator for when to add more food?

    • Not the quickest method, but a safe one. Use a mesh bag and place some flakes or pellets inside. Place the bag inside the aquarium and monitor ammonia levels. You can leave the bag for the time it needs to detect nitrates. You can add and replenish the food in the bag every 2-3 days. As soon as the ammonia and nitrite levels drop back to zero, you can remove the bag.

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