Foreword:

If you're like most of us, you got your first aquarium without much thought or research, if any. After all, how hard can it be? The clerk at the fish store or pet warehouse briefly told you how to set up the tank and you were sent off on your own with a new tank, some water conditioner, plastic plants, and your pretty new fish.

So you brought your fish home and everything was wonderful for the first few days. Then the water turned cloudy and the fish were looking sick - gasping at the surface for air or just huddling in the corner, frightened by every movement in the room. So you frantically got online and ended up here, discovering that the people there were talking about a cycle. Cycle? What cycle? The salesperson never mentioned anything about a cycle. How important could it be?

The first thing you have to know is that this cycle takes time to establish itself. Going through the initial cycling process with fish in the tank takes not only time but lots of effort on the part of the fish keeper to prevent suffering and permanent damage to your fish.

Theory: You'll need a little information so you know what's happening in your tank. I am just scratching the surface here, and many experienced hobbyists will cringe at this explanation. But now is not the time to go into a long explanation of nitrosomas and nitrobacter. Fish and all other animals secrete waste in the form of ammonia. Ammonia is extremely toxic and caustic substance, which burns both gills and skin, sometimes causing permanent damage and scarring. In the wild the huge volumes of water the fish live in dilute this ammonia well below toxic levels, but in our closed aquarium systems we can't mimic nature and provide a constant stream of fresh water through the tank. Ammonia can quickly build up to levels, which will harm or kill the fish. We need help, in the form of bacteria. The "cycle" we refer to is the processing of growing these bacteria in sufficient numbers to process the waste produced by the inhabitants of your tank. The processing of ammonia is a two-stage process. The first stage is growing the bacteria that process ammonia to nitrite. Nitrite is also a toxic substance, reducing the fishes' ability to absorb oxygen in their blood. Even at low levels, nitrite can cause permanent harm. The next stage processes the nitrite into nitrate, a much less toxic substance that is removed with water changes. The two strains of bacteria attach themselves to surfaces; this means any and all surfaces. The sides of the tank, the surface of the gravel, plants, decorations and, of course, filter media are all surfaces for bacteria to grow on.

Equipment: Aside from the tank, lights, heater, filter, and fish, you'll need some equipment.

The first thing you will need to do is to acquire tests for ammonia, nitrite and Ph at the very least. Aquarium Pharmaceuticals makes a Master Freshwater Test Kit for under $20, which will give you everything you need. This is not to say that they are the only - or even the best - test kits out there. But it is an inexpensive and accurate test kit and available just about anywhere. Being able to test your own water is crucial. Not only can you not trust the people at the store to do it correctly, you will get VERY tired of taking samples of water to the store every day. You will need a gravel vacuum. This is essentially a length of tubing with a larger plastic piece at the end. Your gravel vacuum will become your best friend. Water conditioner - for heaven's sake don't get the kind that enhances slime coats or reduces stress or does anything else. Just simple water conditioner that will deal with both chlorine and chloramines.

Now back to those fish. Don't panic. It's a lot of work, but you can do it, and here's how.

Test the water your fish are in for ammonia and nitrites. Don't read the rest of this until you know where you are now. If the ammonia is over 2, change 40% of the water in your tank, replacing it with conditioned water. If your ammonia is over 4, change 50-60% of the water. In other words, change out enough water to bring the ammonia levels down to between one and two, lightly vacuuming the surface of the gravel. Now repeat this process at least twice a day, morning and night. After a couple of week (yes, WEEKS) start checking the nitrites, too. Suddenly one day your ammonia will read zero and you're halfway there.

Now do more of the same thing, testing for nitrites twice a day and changing out enough water to bring the levels down to around 1. This daily grind will seem to go on forever and you will begin to think your tank will never cycle. Truly, it will end, and it will end fairly suddenly. One day you will notice that your readings after 12 hours are much lower. Within a very short time your nitrites will read zero.

Home free, right? Yes and no. You will notice that I call this process the "initial cycle". In truth, the "cycle" never ends. Keeping your tank healthy will be a constant balancing act between fish, waste and bacteria. The bacterial colonies in your tank will only grow large enough to process the wastes produced by the fish that are in there. If you start out with six small fish during the initial cycle and then plunk twelve large fish in the tank, you will get what is called a "mini cycle" while the bacterial colonies catch up with the new "poopers" in the tank. Add your fish slowly and allow for a couple of weeks in between additions. Also, until the tank acquires a good layer of bacterial slime, it will be touchy. A more thorough cleaning of the surfaces than usual can cause a small spike.

Extras: You will hear a lot of people suggesting that you buy potions and powders to help you cycle your tank. I will take these one by one.

• Bacteria in a bottle.
  Cycle, Fritz-zyme, StressZyme and other similar products are touted as being the answer to your prayers. In fact, they can help a bit short-term, but really don't do a lot during the initial cycle. They are quite expensive, need to be added constantly, and are of limited effectiveness. My advice? Save your money and change more water.
• Bio-Spira.
  The exception to the "bacteria in a bottle" products appears to be Bio-Spira. Again, it is expensive, difficult to find, and needs refrigeration, but some hobbyists have reported good luck with it. If you can find it, it may be worth a try. This is NOT a recommendation - I have never tried it. If you do decide to use it, keep an eye on your tank for several months. People have reported unexplained elevated nitrite levels long after the tank should have completed its initial cycle.
• Amquel water conditioner.
  Amquel converts ammonia in to much less toxic ammonium. It is a very good product and does exactly what it purports to do. However (you knew there was a catch) there are drawbacks. First, Amquel is an acid. If your water is soft, it can lower your Ph precipitously, causing Ph shock in your fish. Second, you will need a different ammonia test. Amquel can cause false positives on a regular (Nessler) test. If you decide to use Amquel, be sure you have sufficiently buffered water (check the Kh or carbonate hardness - it should be above 5) and buy a salicylate test. Kordon makes a good one. You won't need a separate dechlorinator.
• Prime water conditioner.
  This is my favourite. Prime water conditioner also converts ammonia to ammonium (you'll still need the salicylate test), but it also helps reduce the toxicity of nitrite. Unlike Amquel, it does not affect the Ph of the water. Follow the directions carefully.

Summary:

As I said earlier, cycling with fish is a long a tedious process but it can be done and at the end of all that work you'll finally be able to relax and enjoy those fish you bought so long ago. If you cycle with fish, your introduction to the hobby can be drudgery and worry, but don't let that put you off this wonderful hobby.