One of the things I am finding now that I have actual fish for which I am actually responsible is that I am totally paranoid for their well-being.

Bad WaterApart from their tendency to play dead whilst resting on the gravel (they both do this) and to raise my panic levels several notches by completely hiding when I want to check that they are still there and still alive… There is Bad Water to worry about.

The thing about Bad Water is that it is a completely invisible – at least until such time as the fish start showing symptoms of being harmed by it, anyway – and also a very fast-acting killer poison. This isn’t like looking after a toddler, when you can tell it’s in danger by the way it keeps playing with knives. It feels like trying to protect my little ones from an Invisible Menace, detectable only by chemical tests in which you have to place almost total faith.

One such poison is ammonia. Essentially, fish tank waste (pee, poo, decaying leftover food etc) pollutes the water with ammonia. Ammonia is VERY toxic to fish, and fish are producing it all the time!

In a mature tank this is not a problem, but to get to be a mature tank you have to go through a cycling process. I have alluded already to tank cycling. It is the process by which any new tank establishes a colony of helpful bacteria to process ammonia, via what is usually referred to as the Nitrogen Cycle. First, some bacteria break ammonia down into nitrites. Unfortunately, nitrites are also poisonous, but fortunately another kind of bacteria just loves nitrites and can process them into nitrates. The nitrates are not harmful until they reach quite high concentrations, and levels can be kept within safe limits very easily by small, regular water changes.

Here is a pretty diagram (click on the link to take you to the source, on

And here is the same thing in a flowchart:

Fish & stuff (plants, leftover food) create waste which turns into… Ammonia, which is extremely toxic to fish, but gets broken down by nice bacteria into… Nitrite, which is nearly as toxic but which happily gets broken down by some other nice bacteria into… Nitrate, which is not very toxic and can help feed the plants but eventually must also be removed by… Water changes, removing some of the aged water in the tank and replacing it with fresh.

Phew, it all makes sense now?

The only trouble is, that with a new tank you haven’t got a colony of helpful bacteria to process the ammonia for you. Fortunately, the little buggers live everywhere so if you give them a quality source of ammonia it is only a matter of time before they will start using it to build a little bacterial citadel. Cycling is the process of establishing the nitrogen cycle, by encouraging a colony of the right bacteria to grow, by providing them with a quality source of ammonia.The problem is that while the colony is still establishing itself, you don’t have enough bugs to process the ammonia that your fish are producing in the tank.

Hence any fish in your tank are at risk of ammonia poisoning. Hence my total paranoia.

You see, it’s complicated. But real.

In fishless cycling, you solve the problem by introducing ammonia into the tank before you actually get any fish. That way no fish can die. However, I didn’t read that chapter until too late and am relying on the traditional method with my little cherry barbs as brave little vanguard ammonia factories.

Using aforesaid chemicals, I am monitoring my poison levels carefully, so I can fix things before anything really bad happens. But, putting my faith in test bottles and colour charts is a bit scary. Poor fish!

It’s a thrill a minute!

Here are some articles about cycling and how to do it, some of which have further links for those who need to know more: