How to keep a goldfish and in which aquarium? The goldfish aquarium is a freshwater aquarium specifically designed for the maintenance of several goldfish. First of all, it should be taken into account that it is no different from any other freshwater aquarium. It has the same requirements for the maintenance and/or rearing of any other freshwater fish. The mistakes made are the same as for any novice aquarist.

How to maintain goldfish in aquariums? What water is needed for them to live long? What should we feed them? What volume of aquarium for 1 or 2 goldfish? These questions are answered here.

The goldfish aquarium consists of the usual technical elements such as a spacious bare tank, a filter for the biological purification of the aquatic ecosystem, and aquarium lighting that operates for 10 to 12 hours at a time. See also goldfish in aquariums.

The aquarium specific to goldfish can be arranged in a simple way, an aquarium decoration simplified enough (design or original) to enjoy the beautiful colors of the various breeds of goldfish. If the biological filter is important, the bubbler is not mandatory, or even not recommended if the aquarist wants an aquarium planted with pretty aquatic plants. Here, the bin is bulky with more than 250 litres.

What equipment for the goldfish aquarium? The goldfish aquarium may (or must) include a heater to maintain the water at a temperature above 18°C. While goldfish can live below this critical temperature, tropical aquatic plants would not tolerate too cold maintenance conditions.

How to keep goldfish in an aquarium? To preserve the fish as well as possible, a layer of sand, if possible thin enough, or round non-cutting gravel, must be installed at the bottom of the aquarium to create not only the decoration of the tank, but also to plant aquarium plants. See also beginner plants and real plants with goldfish.

Tips with the goldfish aquarium:

No one is perfect, we all make mistakes. Here are twelve tips to follow to avoid serious mistakes with a goldfish aquarium. Indeed, in general, new goldfish owners make a lot of mistakes when they get their first goldfish and install it in their first aquarium! Yes, ideally, everyone should look for the right way to take care of fish and operate their freshwater aquarium properly before they catch their first fish, but the lack of knowledge (who knows nitrogen before hearing about it in aquariophilia?), combined with the bad advice from some pet stores, often implies that this is not the case.

The important thing, of course, is to learn and then become better goldfish owners over time. It means learning not only from our own mistakes, but also from the mistakes of others. And that’s why we’ve compiled this list of 12 mistakes with PRs turned into tips to help novice aquarists learn from the mistakes made by others.

Buy a real aquarium of more than 50 litres!

Why not buy a jar? The most common mistake is buying a goldfish jar rather than buying an aquarium that is not a nano-aquarium. The first advice is therefore to admit that a goldfish measures more than 15-20 cm when it is a mature adult, it needs the volume of water accordingly, at least 30 litres per fish, and ideally at least 50 litres per individual for good swimming breeds.

Do goldfish need a large aquarium? Yes! Goldfish need a large aquarium. You should never keep goldfish in a jar!

Why do goldfish require a large aquarium? It is important to realize that the goldfish you buy in your local pet store are very young and have not reached their normal size. See how a goldfish grows! You may be surprised to know that common (ordinary) goldfish can reach up to 25 cm and fancy goldfish can reach up to 18 cm, so you absolutely need a large tray! This volume-length rule avoids the horrible spatial dwarfism.

What a typical goldfish for the beginner:

The first goldfish of a novice aquarist is often this double-tailed variety for the sail-shaped dorsal fin: it is a “Chinese sail”.

The recommended volumes and sizes of goldfish aquariums are:

Fancy red fish: an aquarium of at least 50 litres and 60 cm in length for a single (and unique) specimen. Add 30 litres for each additional PR and increase the length of the aquarium (80 cm for 2 PR, 100 cm for 3 PR, etc.).

Common goldfish: an aquarium of at least 80 litres and 80 cm in length for a first fish. Add 50 litres per additional PR and the length must also increase accordingly (100 cm for 2 PR, 120 cm for 3 PR, etc.).

It should be noted that common goldfish are often more suitable for a pond once they have become larger to allow them to swim. Very few people have an indoor aquarium large enough to properly keep a fully developed goldfish! Remember that the length record of a PR is 43 cm!

Finally, don’t forget that your goldfish tank needs a filter! Even a large tank will be polluted very quickly if it is not properly filtered or if you do not make enough water changes. If possible, get an external filter, as they have a larger filtration volume than the internal filters, and install it outside your aquarium so as not to occupy valuable space inside the tank.

Don’t put too many fish in the aquarium!

How many goldfish can I put in? As mentioned above, goldfish need a lot of space (volume) and can quickly pollute the water: they are good swimmers (they use a lot of energy) and eat like gluttons. Be careful not to overload your bin: overcrowding should be avoided.

Calculate the size of your aquarium (if it is not a ball aquarium) and discover how many goldfish you can keep with our aquarium size calculator.

Don’t rush to introduce the fish!

So you decided to get a goldfish as a pet, you bought a suitable aquarium, a fairly large filter and maybe some food, plants and aquarium decoration… all you have to do now is rush to the pet store and choose your new fish, right? Wrong! Wrong!

When to introduce goldfish into the aquarium? Another very important step is the cycling of an aquarium, which you must follow in order to give your fish the best chances to live a healthy, happy and long life. This may seem complicated at first, but don’t worry, it’s not that bad and the cycling (nitrogen cycle) of your goldfish tank is very important, so be patient!

Like all animals, goldfish produce waste. This is not a problem for them in nature, because there is so much water in rivers and the sea that their waste is diluted and does them no harm. However, in an aquarium, even a very large aquarium or even a garden pond, their waste will accumulate in the water (even if you make many water changes) and their health will suffer.

This is where cycling comes in! When we talk about “cycling the aquarium”, we are talking about the formation of a colony of “good” bacteria in the aquarium, most of them in the filter (the bacteria attach themselves to the filter media) and the gravel sand. These bacteria cause the “nitrogen cycle” and make the water safe (clean) for your fish.

At the beginning of the aquarium, it is necessary to follow the evolution of nitrites to detect the nitrite peak using an NO2 kit. As soon as this peak is detected, with a NO3 test, check for nitrates. When the nitrites are at 0 and the nitrates very low (less than 10 mg/l), the aquarium is cycled for the first time.