Common Aquarium Problems

Thinking about an aquarium? It can really be a wonderful addition to the home. But be sure to inform yourself about the common aquarium problems you might encounter first.
Common Aquarium Problems
Francisco María García

Written and verified by the lawyer Francisco María García.

Last update: 22 December, 2022

Having an aquarium at home for fish has always been popular. Fish are relatively easy to care for and an aquarium can also form part of the decoration at home. However, some people plunge straight into this without understanding the common aquarium problems that you can come across.

The ecosystem of an aquarium can have some significant drawbacks and put your fish’s life at risk. Some of these will be noticeable and the solution isn’t always simple.

As a result, it’s important to know about these potential problems so that you can take the best care of your fish. You want an aquarium that is healthy and looks healthy.

High levels of ammonia

This problem is difficult to notice. Even with a high concentration of ammonia, the water is usually the same color and there are no obvious changes in the ecosystem. However, if this happens, there’s a serious risk of poisoning your fish.

When you first fill your aquarium, the ammonia levels will rise. This means that it’s not a good idea to put your fish in during the first 2 or 3 weeks after filling it. But the main reason ammonia increases is because the water hasn’t been changed in a while or there’s a problem with the filter.

An example of algae, one of the common aquarium problems.

The best way to avoid this is to change part of the water from time to time and make sure that the filter is working. This problem is also likely to happen if one of your fish dies or if you have too many fish in the tank.

Unwanted algae

Having marine plants is good, but if they appear by themselves this is normally a bad thing. This is usually caused by high levels of phosphate or too much sunlight.

There’s sometimes a certain amount of phosphate in tap water, so it’s a good idea to check the levels when you fill up the tank to stop this happening.

However, if the algae have already appeared and you want to get rid of it, there are two practical ways to do this. Firstly, you could add fish or other creatures that eat algae. The second option is to add marine plants because they’ll absorb the phosphate.

Green water

This is one of the main problems you can have with an aquarium. In fact, it’s normally a consequence of the algae problem, with algae suspended in the water to give it a green color.

It’s possible to buy special products that make these algae fall to the aquarium floor. But it’s much better if you can get to the root cause of the problem: too much phosphate, sunlight, etc.

You can help avoid this situation by keeping your aquarium out of the sunlight.

Aquarium fungi

Another common problem with aquariums is fungi. They can directly affect the fish, attaching to the mouth or other parts of the body. They’re also visible to the naked eye in the form of white spots.

This is really a disease for the fish, and the best way to avoid it is with regular maintenance: changing the water, checking the filter, etc.

It’s possible to get antibiotic drops which can help your fish if they’re suffering from this problem.

An well-decorated aquarium.

A bad smell is one of the most common aquarium problems

This is one of the main problems with an aquarium and many people experience it at least once. The smell is normally caused by excess food or keeping too many fish in the tank

The solution depends on the cause of the problem. If you have a lot of fish, you’ll need to get a larger tank. Otherwise, you’ll need to take greater care with the amount, and quality, of the food you use.

This problem could also be solved by changing the carbon in the filter or changing the water. When washing the tank or its contents, be careful not to use too much soap. This could easily poison your fish or kill useful microorganisms.

One final problem that can happen is that the water turns brown. This can happen when placing logs in the tank. But otherwise, as you can see, most problems are the result of poor maintenance and care. Take your aquarium seriously, look after your fish’s habitat, and you’ll have nothing to worry about.


This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.