These Bacteria perform One function. They 'consume' the toxic ammonia that the fish excrete and by a two-stage process convert it to a non-toxic nitrate.

The ONLY purpose to the hardware that you purchase, whether it is an outside box filter or an undergravel, is to facilitate the health and growth of these Beneficial Bacteria. These Bacteria only thrive in the presence of flowing, oxygenated water, and they need a surface to cling to.

Hence, flowing water - from the surface to add oxygen, through the filter medium (upon which the Bacteria grow) and back up, creating the cycle of life for your aquarium. The better the water flow, and the more surface area that is provided for them, the bigger and badder the Bacterial colony. With the undergravel filter, it is the gravel itself that becomes the surface area.

Your Bacterial colony will grow to accomodate each new member of the tank - but it GROWS SLOWLY, so it is vitally important that you add NO MORE THAN 2 INCHES OF FISH PER TEN GALLONS OF WATER TO NEW TANKS. And unfortunately, be prepared for losses, because while the Bacteria is establishing itself, water conditions within the tank get pretty rough. On the next page I will list a few good, tough, starter fish. More on those later.

Then comes the hard part... waiting....

Just think of it like this, a healthy aquarium is like fine whiskey, it needs to be left alone to age well. Feed very sparingly and have your water tested in about 3 weeks to check the progress of your Bacterial colony. Any Aquarium shop worth its salt will know from your water test how far along your tank is - and whether it is safe to add more fish or not.

Now you know why washing your gravel- or emptying your tank- is devastating. You are KILLING YOUR FILTER. And most likely killing your fish as a result.

Too many times I have had people come to me and say "I keep washing my tank out and a few days later its cloudy again! And all my fish DIED! Then I went out and bought 10 MORE fish and THEY all died!!"
Yes, I suppose so.

Now I know you are saying, "Ok, then WHAT do I DO?" Look below for a short list of questions and answers. If you have any other questions, feel free to email.

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HOW DO THE BACTERIA GET IN THERE IN THE FIRST PLACE?

Is usually one of the first questions I am asked. That is simple as well, the First Fish you put into the tank bring it with them. Little carpet baggers :) Your first indication of Bacterial growth is cloudy water for a few days. In this case, cloudy water is a GOOD THING. It will settle out in about 72 hours.

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THEN HOW DO I CLEAN MY TANK?

Simple- you don't.

You do a partial water change of 25% every 4 to 6 weeks (4 weeks for smaller tanks).
Use a 'gravel washer' that sucks the detritus (crap) from the bottom of the tank while siphoning 25% of the water out. Replace it with water that is the SAME TEMPERATURE to which you have added a chlorine remover.
You can pick up a gravel washer from any pet shop for no more than about 6 bucks. Its a fat plastic tube connected to a slimmer, flexible siphon hose. The directions are on the back.

Don't bother to do this till your tank has been set up at least 4 weeks or so.

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WHY SHOULDN'T I REMOVE MY FISH?

Why should you?

I will let you in on the number one top secret about fish. They HATE Change.
Any change in water, temperature, ph, etc., sets them into a total tailspin of stress and angst. Stress lowers immune functions leading to illness.
Fish need good food, plenty of space, interesting surroundings, sex occasionaly and STABILITY.
They are much like us in this way. For this reason, it is always easier and cheaper in the long run to get as big a tank as possible. It is much- much harder to keep fish alive in a 5 gallon as opposed to a 29 gallon and up.

I have noticed a common fallacy among tank owners that when they add a few new fish, and suffer a loss - they immediately blame the new fish for 'bringing disease into the tank' when actually what is happening is that the bacterial colony has to grow to make up for the new fishload of waste, this spikes the ammonia level up and changes the water chemistry. Meanwhile, new territories have to be sorted out between the newbies and the old timers. Contrary to common knowlege, most fish carry about every sort of disease they can die from within thier own bodies.

It is the CHANGES that they are subjected to that bring about the illness.

A couple of hints to ease new fish. Add them in dim light. Turn off the tank lights. Give them a chance to get used to the water before having to deal with the established fish. Coo softly into thier little ears.Make sure they have plently of hiding places. Add only a few at a time.
(kidding about the 'cooing, but ..it certainly won't hurt :).

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**unless they are laying on the bottom with a glazed look to thier eyes- and you note they have not moved for a few days.