How to take care of a goldfish?

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How to Take Care of a Goldfish

Goldfish are soothing animals that require little maintenance. They are often favored by novice breeders. However, they require as much care and equipment as most aquarium fish, as the traditional goldfish bowl can kill your fin friend. Whether you want to raise a goldfish, adopt a pet or just know what it looks like, you need to know how to make it happy and keep it healthy for years (and maybe even decades) to come!

Choosing an aquarium and maintaining it: Steps to follow

Buy a large enough aquarium

The minimum size of the aquarium for 1 goldfish is 56 L (don’t forget that it can reach 25-30 cm and sometimes more!) And you will need to provide 37 L of water for each additional fish. Research the different types of goldfish. Common goldfish, comets, and other single-tailed goldfish need a pond or huge aquarium to reach 30 cm or more. Don’t buy single-tailed goldfish if you don’t have a 680 L aquarium lying around or a pond you can put them in when they get too big.

  • For decades, it was said that goldfish were able to live in small jars and that is why they were known for their low life expectancy. However, goldfish live today as long as a dog! Without sufficient filtration, ammonia quickly accumulates in such a small space and the environment becomes toxic.
  • The goldfish grows according to the space available, however, it does not have to reach its maximum size. Your 2.5 cm fish can eventually reach the size of your arm, but this will only be possible if you put it in a large pond or professional aquarium.

Prepare the aquarium

Prepare the aquarium before buying the fish. Time and attention are needed to create an ideal habitat for goldfish. As noted below, there are several steps you can take to make sure your water and living conditions meet your needs.

  • Fish are sensitive creatures that stress when they move from one environment to another. Too much change in too short a time can kill them even if the living environment is ideal. Do not transfer your fish from one aquarium to another.
  • Goldfish cannot live long in reduced environments (such as a plastic bag or a small bowl). It is possible for 1 hour, but to avoid it if more than a few hours. Do not keep your fish for more than a day in a small container of water.
  • In an emergency, a large, well-washed plastic bucket filled with water treated with a conditioner will do the trick.

Use gravel

Use gravel that is not likely to get stuck in your fish’s throat. Goldfish are particularly at risk of having gravel in their mouths. Use either coarse gravel (too large to swallow) or very small gravel. Large gravel is more suitable for goldfish because it is not likely to be blocked in their throats since they like to search the ground for food.

  • Clean the gravel before putting it in the aquarium. Most aquarium gravel should be rinsed off as the water may be dirty or cloudy. Even if you just bought it, rinse your gravel and soak it for a day in water to remove impurities and be sure that your goldfish has the best environment to flourish. Be careful not to use soap.

Make sure the aquarium is decorated and lit

Goldfish are diurnal animals, which means they are active during the day. They need light to have a healthy sleep cycle and to keep their colors bright  [1] [2]. Fish that don’t sleep well or don’t get enough sunlight will lose their color and become pale. Keep your aquarium lit 8 to 12 hours a day to recreate the natural cycles of day and night if it is not receiving natural light. Never expose it directly to the sun, as this can cause large temperature variations and encourage the proliferation of creeping algae.

  • Place a stone or piece of wood with artificial greenery in the water. Stone or wood gives the fish corners and cracks to explore while artificial plants do not grow and therefore do not risk invading the aquarium. Goldfish thrive with minimal decoration. They are most often chubby and are poor swimmers, which means that with fewer obstacles, they can swim freely. Place a medium or large object in the center of the aquarium and plastic plants outside the swimming area to give your fish maximum usable space.
  • Real plants are beneficial as they absorb ammonia, nitrites, and nitrates which accumulate in the aquarium due to waste and natural wear and tear. However, goldfish are voracious eaters. Use artificial plants until you have the time and resources to protect real plants from hungry goldfish.
  • Make sure your decorations are not hollow (at the risk of favoring the proliferation of potentially dangerous bacteria) and do not have sharp edges (your fish may injure their fins).
  • Use fluorescent lights in your aquarium. Halogen and incandescent lamps will also do the trick. Pay attention to the amount of light you give your companion: goldfish enjoy 12 hours of light and 12 hours of darkness.

Install a water filter

Goldfish need a water filter. The filter plays 3 roles: mechanical to remove large particles (fish droppings or food scraps), chemical to remove odors, discoloration, and organic and biological materials to remove waste with good bacteria and ammonia. The filter must be adapted to the size of the aquarium. If you hesitate between 2 different flow filters, it is better to opt for the more powerful model. Clean water and an efficient and functional filtration system will keep your fish happy and healthy. 3 types of filters are widely used.

  • External power filters which are hung on the edge of the aquarium and which pump water to return it filtered. They are widely used, offered at low prices, and probably offer the best value for money [3].
  • Canister filters are installed under the aquarium and use different tubes to filter the water. They are silent, cost a little more than external power filters, but are more efficient than the latter. Canister filters are designed for aquariums larger than 190 L and are therefore not suitable for small aquariums.
  • Dry/wet filters use an overflow box to filter out impurities. However, they are larger than external power filters or canister filters and are more suitable for aquariums that contain at least 190 L of water.

Fill the aquarium

Once your aquarium at home, fill it with tap water previously treated with a suitable conditioning solution. You can also use distilled water.

Untreated tap water or drinking water contains chemicals and minerals that are harmful to fish.

Set up a nitrogen cycle

Set up a nitrogen cycle before installing the goldfish in his new home. A nitrogen cycle is to pour ammonia into the aquarium and monitor the nitrate levels to make sure the water is safe. Unfortunately, many fish die after being introduced to their new aquarium due to ammonia and nitrate poisoning. Be sure to use a dechlorinator, as chlorine in tap water can kill your fish.

  • Before putting the fish in the aquarium, you need to make sure that the environment there is ideal. Buy a pH test kit and test your aquarium for the right amount of ammonia, nitrite, and nitrate. In the end, you should have 0 ammonia, 0 nitrite, and less than 20 nitrates. Test strips are difficult to use correctly and are quite expensive. Instead, buy a liquid test kit like the API Master Test Kit.
  • The first step is to continuously add drops of ammonia. This initiates the process of transformation into nitrite and if you continue, you will eventually see nitrates that are consumed by algae and plants. Once the process is complete, your goldfish can return to their new home!

Enough talk about Choosing an aquarium and maintaining it. Let’s talk about Caring for and feeding your goldfish:

How to take care of a goldfish

Put the fish in his aquarium

Hopefully, your goldfish (if you have more than one) will be the same variety. Unfortunately, goldfish are known to eat other smaller fish and to eat a lot while leaving nothing for their fellows. If another fish is smaller or slower, it will have no chance. Use a commercially available aquarium divider to separate the “raw” or weaker fish from the rest.

  • Goldfish can be a flourishing fish in the community, but their roommates must be chosen with care. Poor Neon or zebrafish are excellent choices, as is Pleco. However: these fish live in schools and if you plan to buy them, you will have to buy at least half a dozen. In summary: put your goldfish with other goldfish.
  • All new fish purchased from a pet store must be quarantined 2 weeks in advance. If they have any disease, you probably wouldn’t want them to contaminate your healthy fish!
  • Remember that goldfish like colder waters, unlike most other fish that live in communities. The other species you plan to add to your aquarium must, therefore, be resistant. You can also put your goldfish in an aquarium full of viviparous fish that will eat unwanted offspring and prevent overpopulation of fish in the aquarium.

Clean the aquarium

Clean the aquarium at least once a week even if it doesn’t seem dirty. Goldfish produce droppings that even your filter cannot eliminate. A clean aquarium means a happy and healthy goldfish. A happy and healthy goldfish lives for decades  [4]! Soap is poisonous to fish and can kill them. So do not use soap to wash your aquarium and avoid filling it with tap water. Drinking water is also to be avoided because it does not contain the minerals essential for goldfish. Buy a water conditioner from a pet store and use it according to the manufacturer’s directions.

  • Do not remove the fish from the aquarium during cleaning. Use a vacuum cleaner to remove debris from the gravel without removing the fish from its habitat. If you have to remove it from the aquarium for any reason, use a plastic container instead of a net if possible. The net can damage the fins, unlike the container. Besides, goldfish are afraid of the net and you may stress them out  [5].
  • Renew 25% of the water every week assuming that you have properly prepared your aquarium. Renew 50% of the water each time the nitrate levels reach 20. It may be useful to have old towels handy for this messy operation. Just be careful not to suck up small fish when changing the water.

Measure ammonia, nitrite, and pH

Do you remember the test you did before putting your little fish in the aquarium? You will have to do it again! The ammonia and nitrite levels must be at 0. As for the pH, it can be between 6.5 and 8.25.

Feed your fish 1 or 2 times a day

Give him only the amount of food he can eat in a minute. What is written on the product packaging is false. Goldfish can easily overheat and die. It is always better to undernourish them than the reverse. If you use floating food, soak it for a few seconds in water before serving. It will sink, which prevents your fish from swallowing air while eating and therefore prevents buoyancy problems.

  • Like humans, goldfish need to diversify their diet. Give your fish pellets regularly and sometimes give them live food such as artemia. Also, give him freeze-dried food from time to time such as mosquito larvae or bloodworms. Remember to soak the freeze-dried food in a cup of aquarium water before giving it to your fish. It can swell in your stomach and cause buoyancy problems.
  • Give your fish only what he can eat in 1 minute. Remove leftover food, as goldfish die from overeating more often than any other fish.
  • Feed him at the same time each day (once in the morning and once in the evening) and in the same place in the aquarium.

Turn off the lights and let him sleep

Goldfish have no eyelids and never really stop swimming, but their bodies go into hibernation. You see that they sleep when they change color slightly and are less active (they stay on one side of the aquarium).

  • Goldfish like to sleep in the dark. A lit aquarium is only necessary if you are growing plants or if the room where it is located in poorly lit. Even if you don’t have a lit aquarium, it’s good for the environment to reduce unnecessary energy consumption by turning off the lights.

Let the water temperature vary with the seasons

Goldfish do not like temperatures above 24 ° C, but they like seasonal changes during which the water does not exceed 15-20 ° C in winter. Also, note that they do not eat below 10-14 ° C.

  • With a good thermometer, it will be easy for you to monitor the water temperature. You can choose between 2 types of thermometers: those that are hung inside the aquarium and those that are hung outside. The 2 are precise enough, but the idea remains the models that hang inside.
  • If you do not want your goldfish to reproduce, a temperature maintained at 23 ° C throughout the year is perfect. If you want them to breed, simulate the seasons (goldfish spawn in spring). Start by lowering the temperature (hey, guys, it’s winter!) To 10 ° C or 12 ° C. Then, when the moment of reproduction arrives, gradually increase it to 20 ° C or 23 ° C. This signals to fish that they can lay their eggs.

Its time now to solve problems that you can face during all this period:

gold fish

Check the oxygen levels in the aquarium

If you see your goldfish rising to the surface, there may not be enough oxygen in the water. Fortunately, you can solve the problem by reducing the water temperature. Lower the temperature or place your aquarium away from the sun. You can also buy a bubbler or a pump that causes a jet of air bubbles.

  • If you have read everything that has been said before, you are now aware of the most common problems and know how to avoid them! As long as you keep the pH, ammonia, nitrate, and oxygen at a normal level, as long as you don’t overfeed your fish and as long as you keep your aquarium clean, you avoid 95% potential problems that may occur. Good for you!

Clean the cloudy water in your aquarium

Sometimes, even when you put in a lot of effort, things keep going wrong. The water can turn yellow, green, or even white. If this is the case, it is not a serious problem, but still, think of cleaning your aquarium!

Each color variation indicates a different problem. Algae, bacteria, or even residues of plant material may be involved. Don’t worry too much! After another nitrogen cycle or a water change, your fish will be safe.

Look for signs of ichthyophtiriasis

One of the most common diseases in goldfish is ichthyophtiriasis. It causes the appearance of small white dots on the body and the fins and causes breathing difficulties. It is a curable parasite. Put your fish in a hospital aquarium and use a commercially available fungicide.

  • The thing you need to do here is to isolate your fish from other living things, including plants, as the parasite can contaminate plants and animals.
  • If you notice white spots on your gravel or your decorations, remove your filter and treat the whole aquarium. Isolate sick fish, as they will need more attention than healthy fish.
  • You can also use non-chemical solutions, such as increasing the water temperature or adding large amounts of aquarium salt. A temperature of 29 ° C or a tablespoon of salt for 3.5 L of water will eliminate ichthyophtiriasis  [6]. To increase the water temperature (a few degrees per hour) or add salt (1 tablespoon of salt per 3.5 L of water every 12 hours) and continue treatment for at least 3 days after the disappearance of all signs of infection. At the end of the treatment, regularly replace the water to remove the salt and reduce the temperature of the aquarium. Be prepared to see a loss of color or vitality in the treated fish.

Look for signs of trematode infection

Another common parasite in goldfish is trematodes. When infected, they scratch against the surfaces that surround them, develop an outer layer of mucus, blush, and have a swollen belly.

As with any fish parasite (like ichthyophtiriasis), you need to isolate your companion. He can come back to swim with his fin friends after a few days if you deal with the problem quickly.

Look for signs of swim bladder disease

This disease is easy to identify because your fish is leaning sideways or swimming upside down. It may seem dead to you, but luckily it isn’t. Fortunately, too, the disease is not contagious and can be easily treated.

  • In the case of swim bladder disease, it is not necessary to quarantine the fish. This disease is not caused by a parasite. However, you can isolate your fish for more safety.
  • In general, there is no need to use medication to treat swim bladder disease, since poor diet or overeating is often the cause. Give your fish less food or even better, do not give it anything for 3 days. The bacteria in his gut will have time to return to their normal state. If symptoms persist, change her diet to include more fiber-rich foods like peas or cucumbers, or give her a medicine specially designed to treat internal infections.

Take appropriate action if your fish dies

The first thing to do: put your fish in a place where its smell is not likely to spread in the house. You can bury it or, if you feel like it, throw it on a compost heap. Do not throw the fish down the toilet! Take it out of the aquarium with a plastic bag: turn the bag over and grab the fish. Cleaning the aquarium depends on the situation.

  • If there is only one dead fish, chances are you’ve detected the parasite early enough that it hasn’t had time to infect the other creatures in the aquarium.
  • If all of your fish are dying or are dying, you will need to thoroughly clean your aquarium with a bleach solution. Use ¼ teaspoon of bleach for 3.5 L of water. Leave on for 1 or 2 hours to remove all the toxins, then discard the water and let it dry.

Advice and Suggestions

  • A healthy goldfish has shiny scales and straight dorsal fins. When buying your fish, make sure it is bright and happy!
  • Goldfish sometimes put gravel in their mouths. If you see yours doing the same, don’t panic! Most often, he will spit it out right away! Just avoid buying too small gravel which could suffocate it.
  • A goldfish can easily stay a week without eating. If you forget to feed him for a day or two, there is little risk.
  • The memory of goldfish is not limited to 3 seconds. They remember a lot, you have proof of that every time it immediately comes to the surface when you hear the feed hatch open! Most fish are intelligent.
  • If your goldfish looks sick, wash the aquarium water a little more often and feed it regularly. If the problem gets worse, do some research and read the forums for solutions or take it to the nearest pet store for help.
  • Never put your goldfish in a narrow-top bowl. Because of the circular shape, it may bang against the glass and the too-small opening will not bring enough oxygen into the water. Don’t just watch movies and say, “Okay, that sounds easy! Just put the goldfish in a bowl! No, it doesn’t work like that.
  • You need 75 L of water per fish. If you have 2 goldfish, a 150 L aquarium will suffice for their entire life. But if you have several fish, opt for a 280L aquarium.
  • If your fish has white spots on different parts of its body, it is a disease called white spot disease. It can be treated with a solution that you can easily find in most pet stores.
  • Do not take your fish out of their aquarium just because they have their eyes open and stay still. Fish sleep this way: they have no eyelids and they sleep with their eyes open.
  • When cleaning an empty aquarium, use baking soda. The baking soda removes algae from artificial plants, the edges of the aquarium, gravel, and the filter. Then rinse properly.


  • Never put a goldfish in a bowl or container of less than 75 L unless it is only temporary. Not only is the bowl too small, but it is also difficult to filter, prevents the exchange of oxygen, increases the risk of accidents due to its rounded shape, and slows the growth of the fish. Fish living in jars are exposed to deadly chemicals not filtered out and space problems. The chemicals severely damage their immune systems and kill them instantly or slowly and painfully over the years. Life in a bowl reduces the life expectancy of a goldfish by 80% on average. In human life, it’s only been 15 to 20 years!
  • Goldfish can and will try to eat just about everything. So be careful what you put in the aquarium!
  • Goldfish grow (to about 20 cm, but the exotic varieties are smaller and measure 15 cm) and live between 15 and 30 years. Unfortunately, millions of them die each year due to inappropriate sounds and myths (goldfish bowl, etc.). Take good care of your fish and they will live very, very long.
  • Do not rely on the pictures on the packaging of your aquarium. Almost all show a filled aquarium. However, this promotes problems and significantly reduces the fish’s living space.
  • Be careful of the other fish you put with your goldfish! Do your research and ask your pet store. The skeleton of your companion floating in the aquarium is probably the last thing you want to see. Be careful when asking the seller, because most of them don’t even know what they’re talking about. Prefer instead of forums or care sheets.
  • Stir the sand in the aquarium when you change the water to prevent it from compacting and to prevent the formation of dangerous gases inside.

About Muhammad Usman Babar

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