Q&A for How to Do a Fishless Cycle

Doing a fishless cycle will establish denitrifying bacteria in your tank that will keep ammonia levels in check once you add your fish.

It's the same as any other fishless cycle. Add ammonia, wait for the ammonia and nitrite readings are at 0.

Yes, it is. Betta fish need proper water quality just like all other fish. Ammonia and nitrite levels over 0 will lead to ammonia and nitrite poisoning, which can eventually be fatal. Nitrate readings should be lower that 40 ppm, and less than 20 is even better.

Yes. The chlorine in the water will kill the bacteria you are trying to grow for the cycle.

Yes, do a water change WITH the conditioner/dechlorinator. If you do not add this, the bacteria you worked so hard to get will die, along with the fish.

Yes, this is necessary because some of the beneficial bacteria live on the filter media, and therefore need a constant supply of ammonia (otherwise they will die off).

You can add fish food. Don't remove them, as the decaying food will be the source of ammonia instead.

Yes, guppies are one of the more fragile beginner fish, so always cycle before adding fish.

A temperature of 21–27 °C (70–81 °F) is recommended to resemble their native Amazon environments.

No. The chlorine in tap water kills of the good bacteria. You have to cycle it again.

To test for ammonia and nitrite, you will need a kit, or you can take a sample to your local fish store and they might test it for you. If you don't do a fishless, cycle you risk the health of your fish.

I used Nutrafin "Cycle" liquid to prepare my 5 gallon tank for a betta. I had the water tested and got a good report, then I brought the betta into the tank. This seemed to work well as the betta appears healthy (definitely healthier than when I brought him home) and we have had him for almost a year.

You should still cycle your tank to create the beneficial bacteria that will help get rid of ammonia. Otherwise, you risk ammonia spikes that may cause injury or even death to your fish.

Don't add ammonia when there are fish. Only add it in a fishless tank, or you may poison your fish. See Cycle a Fish Tank for fish-in cycling.

Yes. You should cycle a tank with any fish, and it is especially important with goldfish since they produce a lot of waste.

Probably not.

Unfortunately, it depends on the concentration of the ammonia. The stronger the ammonia, the less you will need. You could try 2 ml and then test. If it's not enough, add more, if it's too much, do a water change.

Fish have survived without it, but cycling is strongly recommended, especially for larger tanks. You don't want to suddenly find out your fish are dying, and cycling neutralizes harmful substances that can kill fish.

No, as long as you clean it in the same aquarium water it came from. Actually, you can clean it in tap water if you dechlorinate it first, but I would only use the water it's already been in myself. Put some aquarium water in a bucket and clean the filters in that.

Get testing strips from your local pet store. Put the strip in the water for 1 second and check the results against the instructions on the package.

Change the water, and make sure it has no pollutants. Then you should be able to cycle it normally.

Yes, this is normal for new tanks. The best thing you can do is wait a few days and then change the water if it doesn't clear.

Test the water after changes to see how much you need to add.

Wash it in the tank water when you do a water change. That way, you don't kill the bacteria in your filter and you won't crash the nitrogen cycle.

You should wait until both the ammonia and nitrite readings are at 0 before you add the fish. Adding your fish to water with ammonia will be putting them at risk.

It depends on where you live. If you live in a cold area then yes, it’s necessary.

Yes. If you must do a fish-in cycle, choose a cheap comet goldfish, they produce a lot of waste and are pretty hardy, so they're good as cycling fish.

You can, but I would not recommend doing so. The only chemically connected reason to do so would be to correct a radical pH fluctuation. This is one of the many nice things about doing a fishless cycle. With no fish in the tank, the ammonia and nitrite content in the water is harmless. This is one of those very rare times when maintenance is not needed.

The safest bet is to start from scratch and cycle your water again.

Yes. It will not, however, not be okay for keeping fish, as ammonia is harmful to fish. I would be concerned as to why the well water contains ammonia.