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Disease Control - Poor Water Conditions

Contents

• Nitrogen compounds
• Ammonia
• Ammonium
• Nitrite
• Nitrate
• Hydrogen sulphide

Nitrogen compounds are always found in an aquarium to some degree; they are formed whenever soluble proteins are broken down (fish waste, rotting vegetation or left over food, etc.), they emerge as:

• Ammonia(NH₃), extremely toxic to fishes and must be removed or broken down.

Visual signs of fishes succumbing to ammonia toxicity include:

1. Gasping at the surface
2. Cloudy eyes
3. Frayed fins
4. Listless behaviour
5. Increased mucous production
6. Possible internal and external bleeding (if extreme toxicity exists)

Because of the toxic effects of high levels of ammonia, there maybe fatalities, even after ammonia levels are brought under control. Smaller fish have a higher gill surface area relative to larger fish; and are therefore more susceptible to ammonia toxicity.

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• Ammonium(NH₄⁺) is less toxic than ammonia, and is formed when ammonia reacts with acids, therefore, if ammonia is present in the aquarium, as the pH of the water becomes more acidic, then ammonia will become ammonium.

• Nitrite(NO₂^-) is also toxic to fish if it is not removed, levels above 1ppm need to be removed by carrying out substantial water changes. This should be done on a daily basis for a number of days until the nitrite level has reduced to zero.

Symptoms of nitrite toxicity include:

1. Listlessness
2. Gasping at the surface
3. Blood and gills turning brown

Ammonia and Nitrite levels will tend to be at their highest in the first 4 to 6 weeks of establishing a new aquarium. Because of this you should be aware of
new tank syndrome.

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• Nitrate(NO₃^-) is the end product of the nitrogen cycle, and is relatively non-toxic; although in high concentrations can still be a problem. Nitrite is converted into nitrate by the bacteria Nitrobacter, and the presence of nitrates in a fresh water aquarium indicates that the nitrification process is working.

Some of the symptoms of  nitrate toxicity would be:

1. General poor health
2. Poor growth
3. Poor colouring
4. Less tolerance to disease

To get a better explanation of the Nitrogen Cycle click here

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• Hydrogen sulphide (H₂S) is an extremely poisonous gas that smells like rotten eggs; even in small concentrations it can cause a quick death.

It is produced during the decay of organic matter containing sulphur, and by the action of dilute acid on the sulphides (acid aquariums being at risk).
The usual cause in the aquarium is probably one of neglect; by not keeping the substrate clean of dirt and debris, thereby allowing the decay to build up.
An early indication of this problem can be a sudden bloom of algae. The poisonous gas affects the fish by binding the iron of the bloods haemoglobin, which blocks the absorption of oxygen, this causes symptoms, which include:

1. Respiratory problems
2. Gasping at the surface
3. Unusual colouration of the gills

Regular aquarium maintenance, ensuring to clean all debris from the substrate, should prevent the problem arising.

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