Behave
- rapid breathing
- Fish gasp for air at the surface.
- Fish race unusually fast through the aquarium.
- Fish become apathetic.
- Fish are dying for no apparent reason.
causes
Poisoning can be caused by unsuitable housing conditions, but also by external influences.
Housing conditions that can lead to poisoning:
- too high stocking density
- infrequent water changes
- too much feeding
- of animals that died unnoticed
- too small filter
- failed filter
- too much CO2 supply
- rot in the substrate
External influences that can lead to poisoning:
- rot in the substrate
- copper
- chlorine
- detergents and cleaning agents
- insecticide
- solvent
treatment suggestions
In the event of symptoms of poisoning, large and frequent water changes must be carried out immediately. Up to 80% of the water is changed several times a day. This is carried out until the acute symptoms have disappeared. It should be noted that some causes of poisoning are related to the change of water. If one of these causes is suspected, the following instructions must be taken into account.
The exact cause research can be carried out after eliminating the acute problems. For this it is helpful if a bucket of the original aquarium water is kept for later examination before starting the water change.
Examples of poisoning
nitrite poisoning
Probably the most common poisoning in aquariums is nitrite poisoning. Nitrite is formed in the so-called nitrogen cycle in the course of the biological decomposition processes in the aquarium. Nitrite is highly toxic for the aquarium inhabitants and should not be present if possible. With sufficient water changes, nitrite poisoning can normally be prevented. The prerequisite is that the water is not extremely polluted by overstocking, putrefaction or overfeeding. A good rule of thumb has proven to be a weekly water change of at least 25% of the aquarium water if the fish population is not too high. The nitrite content can be easily checked with the water tests available in the aquarium trade. The so-called drop tests are more accurate than the strip tests and should be preferred.
New or newly established aquariums are particularly susceptible to nitrite poisoning. The bacterial cultures required for the breakdown of pollutants must first settle in the filter and in the aquarium. This process is called break-in. Before that, the filter can only work purely mechanically and collect coarse dirt floating in the aquarium in the filter.
For the same reason, a filter should never be cleaned too carefully. The filter material should only be cleaned lightly with aquarium water or lukewarm tap water. Otherwise the valuable bacterial culture will be destroyed and the filter will have to be run in again.
Even after using many drugs, especially after using antibiotics, the bacterial culture is severely damaged and nitrite poisoning easily occurs.
The run-in period is generally estimated to be 4 to 6 weeks. Even so-called bacterial starters do not accelerate the running-in significantly.
If the nitrite levels are very high, the entire fish population can die within a short time. However, nitrite can also lead to long-term damage. The fish can still die after weeks or months. Larger water changes of 50 – 80% are therefore advisable in the case of increased nitrite values.
The nitrite value during the break-in period can rise very quickly, within hours to a day at most. Therefore, 1 to 2 water changes of 80% and more may be necessary in the first few weeks. It may be useful to add table salt because the fish absorb less nitrite through the gills.
nitrate poisoning
Nitrate is formed as a by-product of nitrite in the so-called nitrogen cycle during the course of biological degradation processes in the aquarium. Nitrate is only toxic to aquarium inhabitants in very high doses. Nitrate is used by the plants as a nutrient and can be present in the water up to a level of 50 mg/l, in young fish up to a level of 20 mg/l. Since nitrate is a by-product of nitrite, regular monitoring of the nitrite value is sufficient. Normally, nitrite poisoning occurs before nitrate poisoning. However, nitrate is already present in tap water. Therefore, the basic value in the tap water should be measured or requested from the responsible waterworks. If this value is already close to the maximum value, the nitrate value should also be monitored regularly.
Ammonium and ammonia poisoning
Ammonia is formed from the ammonium at a pH value of 7 and higher. The higher the pH value, the more ammonia is formed. At a pH of approx. 9.4, there is 50% ammonium and 50% ammonia. In turn, ammonium is formed in the so-called nitrogen cycle in the course of biological degradation processes and is itself non-toxic or less toxic according to some sources. Since ammonia is particularly toxic, ammonium and ammonia must not be detectable in the water. Like nitrite, ammonium or ammonia can be removed from the aquarium by regularly changing the water. Since nitrite poisoning is more likely to occur than ammonia poisoning, except at very high pH values, monitoring the nitrite value is usually sufficient.
Possible signs of increased ammonia levels:
- Fish gasp for air at the surface of the water
- Fish swim on the side
- Fish sit or lie on the bottom
- loss of appetite
- Fish have red stripes on their fins
- Fish have red gills
- Fish make strenuous swimming movements
CO2 poisoning
CO2 is produced when fish breathe and is consumed by the photosynthesis of plants. Since plants also produce CO2 at night, the CO2 value during the day is highest in the morning and lowest in the evening. However, the biological processes in the aquarium do not lead to a dangerous accumulation of CO2. Many aquarists try to strengthen plant growth with an additional supply of CO2. Since the ph value is related to the CO2 value, attempts are sometimes made to reduce the ph value by adding CO2. Due to this artificial supply of CO2, there is of course the risk of excessive accumulation in the aquarium water. From a level of 15 to 20 mg/l there is a risk of poisoning the fish. 20 mg/l should therefore not be exceeded.
The decisive factor for the occurrence of CO2 poisoning is whether the fish can exhale the absorbed CO2 again. When breathing, the fish’s mouth fills with water. The water is pushed past the gills. Oxygen O2 diffuses from the water into the blood. Carbon dioxide CO2 diffuses from the blood into the water. The concentration gradient of the respective gas between blood and water depends on how much is absorbed or released.
If the amount of oxygen ingested is not sufficient to meet the need for oxygen, the oxygen content in the blood decreases. As soon as the oxygen level falls below a certain minimum limit, the fish breathes faster. If the fish is getting more oxygen than it needs, breathing slows down. The oxygen content in the blood regulates the respiratory rate.
In many aquariums there is very good plant growth due to strong lighting, good fertilization and the addition of CO2. In such aquariums there is often an excess of oxygen. Because the fish can absorb a lot of oxygen through the gills and skin even without strong movement of the gills, the gill movements of many fish species are hardly recognizable. This shallow, slow breathing quickly equalizes the concentration of CO2 in the water and in the blood. At the same time, less and less CO2 is emitted per breath, although new CO2 is constantly being produced in the body. The more the concentration of CO2 in the water corresponds to the concentration in the blood, the less CO2 the fish can emit.
If there is a lot of CO2 in the water and at the same time shallow breathing due to a lot of oxygen in the water, the fish can no longer release the carbon dioxide produced in the body, although the absorption of oxygen is not impaired. Due to the large amount of carbon dioxide in the blood, the pH value of the blood drops. even small changes in blood pH have major effects on many bodily functions in fish.
The symptoms of too much CO2 in the water depend on a number of factors. Direct CO2 poisoning is an extreme case. In the case of CO2 poisoning, the oxygen content in the water is so low and the CO2 content in the blood so high that the fish can no longer absorb enough oxygen through the gills. The fish suffocates.
At the same time or independently of this, the pH value in the blood can drop so quickly and severely that bodily functions, e.g. B. the stimulus transmission, are severely disturbed.
Even without symptoms of CO2 poisoning, fish can be affected by an unfavorable ratio between oxygen and carbon dioxide. Because the kidney has to correct the acidification, ie the pH value, of the blood, the kidney suffers particularly bad conditions.
The CO2 value can be determined with tests available in pet shops or indirectly, but somewhat imprecisely, calculated from the pH value and the KH value.
In the event of CO2 poisoning, the aquarium should be drained as much water as possible and then slowly refilled with new water. At the same time, oxygen is allowed into the aquarium with an oxygen stone. If the fish are already showing severe symptoms of poisoning, it must be weighed up whether they should be transferred directly to other water. The risk of conversion shock may then be lower than the risk of poisoning.
copper poisoning
Copper poisoning can have a variety of causes. Both algaecides and some medicines contain copper. Since copper is toxic to fish, especially catfish and invertebrates, the use of such agents is strongly discouraged, especially since there are suitable alternatives.
Another source of copper is copper water pipes and water heaters. In apartments with copper pipes and instantaneous water heaters, to be on the safe side, you should let the water run off for a few minutes so that any copper residues are flushed out of the pipe.
chlorine poisoning
Chlorine can be easily recognized by the smell of tap water. In tap water…