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How to keep goldfish alive for 15 years?

The longest recorded lifespan of a goldfish (Carassius auratus) or other aquarium fish is 43 years. An anomaly, since most of these pet fish do not even live a quarter of that time. Interestingly, they are supposed to live as long as a cat. What are we doing wrong?

We use the goldfish as an example because it is one of the most common aquarium fish. It is one of the first fish domesticated by man, being the first time in China more than a thousand years ago, when at the time of the Jin dynasty they were already raised as fish for human consumption and later to be raised in ornamental ponds and gardens. aquatic.

Young goldfish

Be that as it may, today most of these fish don’t even make it to their fifth year, and the usual culprit behind the premature death of pet fish is clearly identified by science: the little droppings.

And is that goldfish waste contains toxins such as ammonia that can burn gills and even damage the brain. In nature this is not a problem. Freshwater lakes and ponds are home to armies of bacteria that break down into less harmful chemicals.

Group of goldfish

However, in the small tank or fish tank of a house, there are no bacteria, in fact, it is the owner who is in charge of including them, and that is where many people go wrong, because you cannot buy a fish the same day that you get a fish tank .

The reason: the bacteria growth process requires patience.

To do this, you must first remove chlorine from an aquarium water with a conditioner. Chlorinated tap water is fine to drink as it kills germs, but it’s not such a good idea for the bacteria that needs to be grown.

Once a safe space has been created for them to grow, they will come from everywhere: the air, the outside of the aquarium, or whatever rocks or plants are attached for decoration. You can also buy commercially available cultures of bacteria grown in labs.

After that, all the bacteria need is to feed. Fish food, for example, is perfect. As it breaks down it releases ammonia for bacteria to feed on. Then just have to wait. Depending on the number of bacteria, the process can take about two months. After that time there should be enough bacteria, something you can check with a simple water test kit.


…not even all the bacteria in the world would be able to keep the fish alive if the tank is too small. The reason: As these bacteria gobble up fish waste, they produce their own waste, and if not diluted enough, they can also kill fish in the aquarium.

To do?

Even the 45 liter aquariums that are usually sold could be very fair. And it is that a single adult goldfish needs at least twice as much water to grow. And even with a huge aquarium, about 30% of the water still needs to be replaced every two weeks, because in addition to droppings, these fish release hormones and pheromones into their environment that, if left unchecked, can stunt their growth.

This could help explain why fish in healthy environments can grow to the size of a football, while fish in an aquarium are typically no larger than a finger.


…and once you have a large enough and detoxified aquarium, the fish only needs one more thing: the owner’s attention. They are often careless and don’t realize something is wrong until it’s too late. For example, with fungal and bacterial diseases and infections that are due if the strain is unknown, treat with amoxicillin for fish or ampicillin for fish. Therefore, it is a good idea to pay attention to how the set looks and, above all, how the water smells.

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