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How to Care for Goldfish

Kate graduated from Sonoma State University with a Bachelor of Science (BS) degree in biology. She currently resides in Sonoma, California.

A happy and healthy goldfish showing off his brilliant colors!

A happy and healthy goldfish showing off his brilliant colors!

Goldfish Care and Maintenance

Despite popular belief, goldfish are actually not always as easy to care for as one might think. Goldfish require a medium amount of maintenance and can be a very rewarding pet, but overlooking a few basic care requirements can lead to an early death for your new friend. Here are some instructions that can be followed to make sure that your little goldfish friend is not only happy, but also healthy for the years (and yes, maybe even the decades) to come!

We will discuss getting ready for your new fish, including tank requirements and other equipment you'll need. We will also discuss the best practices for general upkeep and feeding of your goldfish.

How to Get Ready for Your New Goldfish

  1. Set Up a Properly Sized Fish Tank
  2. Use Properly Sized Gravel
  3. Get Aquarium Scenery and Lighting
  4. Get the Right Aquarium Water Filter
  5. Fill the Aquarium With Water
  6. Cycle the Aquarium's Water
Goldfish in pet stores are often times over crowded in a tank. This is fine for the short term but shouldn't be their daily habitat.

Goldfish in pet stores are often times over crowded in a tank. This is fine for the short term but shouldn't be their daily habitat.

1. Set Up a Properly Sized Fish Tank

The minimum size a tank should be for just one goldfish is 30–40 gallons. If a goldfish is not provided with enough space, goldfish have a survival mechanism that will make them stop growing. The catch to this is that their organs will continue growing while their outsides stay small. This can cause many future health problems.

For each additional goldfish that is in the tank or anticipated to be in the tank, you will need to provide an additional 15 gallons of space. There are different types of goldfish which require even larger tanks, or even ponds, such as comet goldfish or single-tailed goldfish.

Fact: These types of goldfish can grow to be a foot or even more in length!

The proper goldfish habitat can take some time to set up. There are many steps that need to be done to make sure all of the living conditions, including the water, are right for the goldfish.

Habitat Tips

  • Fish get stressed when going from one location or environment to another one. Even in ideal conditions, too much change happening in too short of time can end up killing the goldfish. This is why it is important to buy the correct tank size from the beginning.
  • Goldfish are unable to survive in temporary locations, such as a plastic bag, for more than a few hours.
  • In an emergency, a plastic bucket that is large and rinsed very well with water conditioner and treated water will work.

2. Use Properly Sized Gravel

Goldfish tend to be prone to getting gravel caught inside of their mouths. Make sure that the gravel used inside the aquarium is either very small or too large for the goldfish to swallow. Gravel that is too large to swallow is always safest. Always make sure to rinse the gravel well before placing it into the aquarium so that it does not leave you with dirty, dusty, or contaminated water. Make sure to rinse the gravel with water only and never use soap.

3. Get Aquarium Scenery and Lighting

Make sure to buy a tank hood that has lights already installed or another light that is aquarium specific. Goldfish are active during the day and they need to have light so that they are able to maintain a wake/sleep cycle that is healthiest for them.

Some evidence has also been shown that the light is necessary to help the goldfish maintain their bright colors. The aquarium should be lit for 8-12 hours each day if it is not in an area where it will receive natural sunlight. Make sure to not place an aquarium in direct sunlight, as this may cause extreme temperature fluctuations.

4. Get the Right Aquarium Water Filter

It is very important that you have a filter for your goldfish tank. The filter should contain three stages: a mechanical stage, which will remove large particles like waste or leftover food, a chemical stage, which will remove odors and discolorations, and a biological stage, which will help to break down the fish waste and ammonia.

It is also important that the filter is rated for the size of your specific tank. When a tank is on the borderline of two different filters it is always best to go ahead and get the larger filter rather than the smaller one.

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The traditional "goldfish bowl," while pretty to look at, is not enough room for your new friend.

The traditional "goldfish bowl," while pretty to look at, is not enough room for your new friend.

5. Fill the Aquarium With Water

Once you have your tank set up and ready, fill it with tap water that you treated with a water conditioning solution. These water conditioning solutions are readily available at your local pet store. It is also appropriate to use distilled water. This is because tap or drinking water that has not been treated has different chemicals as well as minerals that may harm the goldfish.

6. Cycle the Aquarium's Water

This type of cycle involves adding ammonia to the tank and watching the nitrate levels to ensure the water is at a safe level for a goldfish to live in. Your local fish store will sell a powder to put in the tank to accomplish this easily.

Also make sure to add in de-chlorinator because the chlorine that is in tap water will end up causing goldfish to die. Pick up a pH test kit and make sure that the nitrite and ammonia levels are at 0 and nitrate is less than 20.

Many goldfish end up dying upon being introduced into their new homes because of nitrate and ammonia poisoning so take the time to ensure their habitat is not toxic to them.

These goldfish are ready for a meal!

These goldfish are ready for a meal!

Upkeep and Feeding Guide

If you have made it past the aquarium setup, let's talk about what happens once you actually have your goldfish in the tank!

  1. Add Your Goldfish
  2. Clean Your Aquarium Regularly
  3. Measure the Ammonia, pH, and Nitrite
  4. Feed Your Goldfish the Right Amount
  5. Adjust the Aquarium Lighting
  6. Monitor the Water Temperature

1. Add Your Goldfish

Goldfish are known to actually eat each other so it is important that if you have more than one goldfish, they all are the same type. Goldfish also can overeat while attempting to keep food from their peers. If another of your goldfish are smaller or even slower, they won't stand a chance getting food, so a tank divider can keep the fish that seems to be the "bully" away from the fish that are a little bit weaker.

2. Clean Your Aquarium Regularly

Even if the tank doesn't look dirty, it is important to clean it. Goldfish produce quite a bit of waste and even the best filter may not be able to remove it all. Goldfish are always happiest and healthiest when their tank is clean and this can help your goldfish live for decades!

Always make sure to never wash the tank with soap because the soap residue is very poisonous to goldfish and will kill them rather quickly. Always avoid taking the fish out of the tank while cleaning.

Gravel cleaners/vacuums can be bought to help clean the debris from the bottom of the tank. I use the TeraPump's Aquarium Cleaner as it is one of the most widely used fish tank cleaners around. It utilizes a simple hand pump so you don't have to suck on a tube and risk getting fish water in your mouth when starting the water flow, and a quick cut off valve so you won't make a mess on your carpet.

These vacuums make cleaning the tank quite easy, but will reduce the water level of the tank during cleaning. It will be necessary to add water back to the tank after cleaning to get the water back to the proper level. Always make sure to use a water conditioner bought from the pet store to ensure that the quality of the water you add back in is the best for the goldfish.

3. Measure the Ammonia, pH, and Nitrite

Remember the test kit you bought to test all of these levels before adding your fish into the tank? Well, the fun continues! You need to keep testing to ensure that the levels remain at an optimal place for your precious little fish. Ammonia and nitrite levels should always remain at 0 and an acceptable pH range for goldfish is between 6.5 and 8.25.

4. Feed Your Goldfish the Right Amount

Feed your gold fish 2 to 3 times per day.

Only feed your fish what they are able to eat in a minute, being careful not to over-feed them! Goldfish can overeat very easily which will lead to a very short lifespan for them. It is always preferred to underfeed a goldfish rather than overfeed them.

When using floating food, soak it in water for a few minutes before feeding the goldfish with it to help make sure that it sinks. Goldfish like variety so make sure to feed them pellets most of the time, live foods only some of the time and freeze-dried just every once in a while. Always soak freeze dried food before feeding it to your goldfish because otherwise it will expand inside their stomachs and cause them issues with swimming.

5. Adjust the Aquarium Lighting

Goldfish don't have eyelids and they actually never stop swimming, but they do hibernate in their own way. They are "hibernating" when you notice them moving less; they will also display a very slight change in their color.

Therefore, it is important to make sure your new friend gets the proper amount of light. Goldfish generally need 12 to 13 hours of moderately bright light each day. A timer for your aquarium's light is best to ensure the right amount of light each day. Remember not to use direct sunlight as it can easily overheat the water.

6. Monitor the Water Temperature

Goldfish actually don't like temperatures warmer than 75 degrees Fahrenheit but they do enjoy the seasonal changes where the water temperature will reduce to the high 50s or 60s (Fahrenheit) during the winter time. Goldfish will not eat below 50–55 degrees Fahrenheit, though. So buy a good thermometer from the pet store to make this part easy!

A Little Work Leads to a Rewarding Pet

Despite popular belief, goldfish can actually be quite complicated pets! They are not an ideal pet for children, nor are they an ideal first pet. To make sure you give your goldfish, or many goldfish, a long and happy life, follow the instructions above! Feel free to refer back or print this article for reference.

It may seem like quite a bit of work, but your goldfish will be much happier and will provide you with their companionship and beautiful colors for years to come.

Questions & Answers

Question: How often should I feed my goldfish?

Answer: It is best to feed your goldfish between two to three times per day, taking care not to feed them more food than they can eat in about a minute. One good rule of thumb is not to feed them more food than the size of one of their eyes.

If you start to see a buildup of uneaten food in the tank, then it is a sign that you are overfeeding them.

Question: Why does my fish tank smell only two days after changing the water and cleaning the tank?

Answer: There can be a few causes of this. Your tank can smell by either being too dirty or too clean. Believe it or not, the most common is that the tank is too clean.

Can it be too clean? Yes, it can.

A healthy goldfish tank relies on a careful balance of good bacteria inside it's ecosystem. What you describe can occur if you change more than 20% of the tanks water at a time, or change all the filter elements at the same time that you change the water.

If it sounds like you may have your tank too clean, give your take a little more time before you change the water next. When you do, don't change more than 20% of the water. Also, try to stagger the water filter changes so they aren't at the same time as the water changes.

If you are using medication in the tank, make sure you aren't over medicating the fish as that can also lead to a foul smell.

© 2017 Kate Daily


Stephen Tang on May 28, 2020:

How to subscribe/join in your goldfish group? Thks.

Sergio from Spain on March 24, 2020:

Very interesting post. Thank you very much!!

Kate Daily (author) from California on March 29, 2018:

If they are in a large bowl and are relatively healthy goldfish, then yes they should be ok for a bit. Goldfish are pretty tough in general. I wouldn't go more than a few days though if possible. The biggest issue is going to be lack of oxygenated water. If you can at least get a small air pump from a fish store in the mean time to get some bubbles going in the bowl, that will be very good for them. If for whatever reason that is not an option, find some other way to get some air into the water. Even of its just taking a cup and scooping/pouring water back into the tank from a foot or two in the air so it creates bubbles and stirs the water when it lands. That is better than nothing, but you really can't do that all day so you should definitely get a pump. A small air pump from a fish store is pretty cheap and that's really the only way I would consider doing it. Also I would change about 30-40% of the water every few days if it's a small bowl and kind of cramped. The bigger the bowl is, the longer you can go without changing the water.

Julie Pollard on March 29, 2018:

Hi - I rescued some goldfish today - long story. I don't have the big tank, filter, gravel etc because I had to go with what I could get my hands on quickly to get them out of the bag. Will they be okayt in a large bowl until I can get an aquarium set up?

Kate Daily (author) from California on December 19, 2017:

Thank you Alexa! They really are a beautiful pet.

Kate Daily (author) from California on December 06, 2017:

Thank you Alexa!

Alexa Rain from egypt on December 01, 2017:

Great tips to look after this beautiful fish, Great Hub.

BellatheBall on November 26, 2017:

And, despite popular belief, goldfish, or carp, continue to grow and can become quite large.

We bought some feeder goldfish and a few that lived got to be more than 6" long within 3 years.

If given the room to grow and the right environment, they can grow into very large fish.

You can even train them to come when you "Call" by tapping on the lid of the tank when feeding.

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