Smelly aquarium, what to do?

Smelly aquarium, what to do? If your aquarium has a foul odor, you are definitely looking for a solution to fix this problem. If an aquarium smells bad it is not without reason. There are several possibilities for this to happen.

Possible causes of the problem:

• Too much nitrite (which may be linked to too much fish).
  
  
• A population too large for the volume of the aquarium.
  
  
• A filter problem or a lack of filtration.
  
  
• A lack of oxygen.
  
  
• Standing water.
  
  
• A dead animal, or a dead plant.
  
  
• A bad substrate in the aquarium.

Each of these causes can stem from different things.

Too high nitrite level:

For the level of nitrites it is possible to test it using different water testers : generally with drops (which is more precise) or with strips. In particular from the JBL brand available on our site:

=> Also discover our guide on water quality testers.

If the test reveals that the nitrite level is too high, it could be due to several things that you can usually improve without the help of any product.

If you have a fish population that is too high in your aquarium, the nitrite level and the comfort of the fish will be strongly impacted. It is therefore advisable to regulate/reduce the number of fish as needed. (If in doubt about the right quantity of fish present in your pool, do not hesitate to ask a specialist).

Too much food due to too frequent feeding or too large proportions can also lead to too much nitrite due to the waste left by excess decomposing food in the aquarium.

A lack of plant could also explain the bad quantity of nitrite.
Indeed it is preferable to add a number of plants proportional to the size of the aquarium and the animal species present in it. But do not add any plant in it either, do not hesitate to find out which species of plants could be suitable, depending on your aquarium and the species that populate it. Dead plants are also sources of bad odors so they must be removed as soon as possible.

Finally, the lack of good bacteria is one of the main reasons for a much too high level of nitrites, you must not forget to inoculate your filter with bacteria which will allow the elimination of organic waste and will therefore prevent the rise of nitrites. It is therefore quite important to maintain a sufficiently large population of bacteria in your pond.

Attention ! Too high a nitrite level can also cause mortality in the aquarium. It is therefore all the more important to check it and adjust it if necessary fairly regularly.

Aquarium population too large:

Depending on the species you have in your aquarium, be it fish, turtles or other animals, the aquarium population should not be too high. Regardless of the species: too large a population is not recommended, as this will affect the quality of the water and the life of the different animals present in the aquarium.

In particular because of the space which will be insufficient for the well-being of the animals and the quantity of waste which will be far too great and will therefore inevitably cause nauseating odors in the aquarium. Moreover, who says more population says more food therefore potentially more decomposing food therefore a higher risk that the nitrite level is too high.

Your filtration system may also no longer be sufficient to keep the water from becoming cloudy.

Filtration problem or lack of filtration:

If you do not have a filtration system in your aquarium it is advisable to add one to filter the water and help keep it of the best possible quality while filtering waste and allowing bacteria (mentioned above) to settle in.

If you have a filtration system, but the smell persists and you suspect the filter to be the cause, it may not be powerful / efficient enough for your aquarium or for the population. present inside it. So it would be better to check if the model you are using is sufficient for your needs.

It can also simply be the cleanliness of the filter which is not sufficient, this could be due to a clogging of the filter, either because of too many things filtered or too infrequent cleaning . (Or again the efficiency of the filter which is not sufficient, so it would have to be changed or cleaned very often, which in the long term does not have a viable solution).

Lack of oxygen :

A lack of oxygenation could also be the cause of bad smell in the aquarium. Indeed, the lack of oxygen can cause the water to become cloudy due to the proliferation of bad bacteria.

Moreover, the lack of oxygen is not good for either the animals or the plants in the aquarium, oxygen is vital for the life and well-being of both.
Too great a lack of oxygen can also cause health problems or even the death of its last.

To overcome the lack of oxygen, it is advisable to add some oxygenating plants in your aquarium which will provide more hiding places for the inhabitants of the aquarium, some of the oxygen necessary for their well-being.

But the most effective as a source of oxygen in the aquarium remains an oxygen pump (also called an air pump), which greatly exceeds the amount of oxygen provided by plants and which allows oxygen to be provided in all circumstances.

=> To find out which air pump is used for your aquarium, do not hesitate to consult our guide on this subject.

Standing water:

Standing water can be a fairly common cause of a bad odor and it usually happens due to lack of water movement, which can be fixed with a water pump and a air pump.

Or a bad placement of these. It is also necessary to check their correct operation regularly and take care not to let them become clogged.
If you do not know where to place your pump in the aquarium we have a small article on this subject:

In addition to these two devices which will create movement in the water, it is advisable to regularly change part of the water in the pool. Maximum 30% water every 2 weeks. But this can vary, depending on the needs and the animals present in the aquarium.

If you suspect the source of the smell is lack of water changes and want to tackle that, be sure to read: our guide to water changes.

A dead animal or plant :

Unfortunately, it happens that an individual dies in your aquarium and whatever the cause of its death it is possible that it is decomposing in a corner. Which would cause waste and strong smell in the fish tank, usually just take it out and the smell will go away on its own after a while.

If you have a few small individuals and one of them has disappeared, do not hesitate to look in every corner, every hiding place or every decor, because it could well be dead out of sight and cause therefore a disturbing smell without you noticing that it has disappeared.

If you have plants in your aquarium it also happens that the leaves or the plant itself dies, which also causes odor discomfort, if this is the case you can either cut the dead leaves of the plant to remove the smell, or if the plant as a whole is dead, it must also be removed and possibly replaced so as not to create a vacuum or lack in the pond, depending on the usefulness of the dead plant.

Some animal species will be happy to get rid of dead leaves from plants without you having to intervene.

A bad substrate in the aquarium:

Not all substrates are good for the aquarium, some kinds of sand or gravel become compacted over time and the waste material inside can end up giving off odors in the aquarium. It is important to choose your substrate carefully so as not to end up with this kind of problem in the long term.

There are different types of recommended substrate, depending on the species present in your aquarium. Do not hesitate to ask your specialist dealer for advice.

And that concludes the main causes of bad odors in aquariums. If none of the reasons mentioned above seem to be the cause of the smell in your aquarium, do not hesitate to contact a specialist about it.