Goldfish Care Sheet: Everything You Need to Know on One Page
When people think about keeping fish at home, the goldfish is definitely top of mind for most. That being said, proper goldfish care is not widely understood.
Now, I like to entice readers with interesting statistics. So, I tried to find out how many goldfish are kept as pets around the world. The best I can do is to tell you that more than 48 million Americans ate at least one bag of Pepperidge Farms Goldfish crackers in the past month.
While this doesn’t help us calculate the world goldfish population, it does speak to the popularity of them and the solid place they have in our collective consciousness. So the lack of knowledge around caring for goldfish properly is a cause for concern.
This article will take care of that.
In this one page care sheet, this complete step-by-step guide on how to care for goldfish, we’re going to give you everything you need to meet all of their needs.
Along the way, we’ll dispel a few myths, let you know what equipment you need, detail how to set up a goldfish tank (yes, tank – never a bowl!), how many goldfish you can keep at once, tips on buying healthy specimen, as well as daily, weekly and monthly maintenance tasks and more!
Keep reading and get ready to enter the wonderful world of caring for goldfish.
Before We Start: There’s 2 Ways to Use this Guide:
For a simple, easy to follow summary of all important goldfish care tips: Please continue to read this page. Everything is here, highly actionable and is all you need.
For a more detailed deep dive into each topic in caring for goldfish: The following links will take you to a new, deep and comprehensive guide on each individual topic:
- The history and evolution of goldfish
- 634 goldfish names to choose from
- What size tank do goldfish need?
- Do goldfish need a filter?
- Do goldfish tanks need an air pump?
- Do goldfish need light?
- Gravel, sand or bare bottom for a goldfish tank?
- What temperature should goldfish water be?
- Cycling your goldfish tank
- What do goldfish eat? How to feed your goldfish
- Best goldfish food
- Best plants for goldfish tanks
- How to change your tank water safely
It all Starts With the Right Tank, Equipment, And Accessories
Walking into an aquarium store can result in sensory overload. There are so many tanks, filters, decorations, and other stuff it can be tough to pick out the gear that you need.
Let’s quickly pare down the choices and get to what is essential.
Choosing the Right Tank for Goldfish
Buying an aquarium for fish is a little like buying a home for yourself; you have to pick one that meets your needs, both present and, if possible, future.
The Rule of Thumb for Aquarium Size When You’re Keeping Goldfish
It depends on the types of goldfish you aim to keep:
- Fancy Varieties: 20 Gallons of Water for the First Fish, Plus 10 Gallons for Each Additional Fish
- Single Tail Varieties: 30-40 Gallons of Water for the First Fish, Plus 10 Gallons Per Additional Fish
Why such a big difference in tank size?
Single tail varieties, like comets or common goldfish, have the potential to grow quite large, and they are incredibly active, swimming fast and often. They’ll need extra room to move around comfortably, both vertically and horizontally.
If you think you’d like a small school of single tails, maybe 4 or 5 total, you’ll need at least a 60-70 gallon tank. For this reason, many fish-keepers see single tails as more suitable for ponds.
So, before you buy a tank, think ahead to how many fish you think you’d like to keep. Consider not only goldfish, but also any tank mates you might want to one day include. (Note: We’ll talk about suitable companions a little later in the article.)
Substrate is, appropriately, the blanket term for whatever material you choose to cover the bottom of the tank. There are many choices available, including using nothing at all. Which substrate is best for goldfish?
First off, we almost always suggest using substrate of some type in your decorative tank, no matter what kind of fish you’re keeping.
Substrate is a breeding ground for bacteria – don’t be alarmed, it’s the good kind! Good bacteria are an essential part of the nitrogen cycle, which we’ll also talk more about later. There are some advantages to having (ahem) a bare bottom, such as being easier to clean, but goldfish prefer it covered up.
This is because goldfish are natural foragers, they like to dig and root around in sand, gravel, soil or anything, looking for morsels of food. It’s a natural behavior, so we should always try to set a tank up for this.
The type of substrate you choose depends on two factors: the fish you plan to keep, and whether or not you want to grow live plants.
Your two basic choices are sand or gravel.
Gravel has many advantages as a substrate. It vacuums nicely, and it has lots of surface area for bacteria to thrive. Goldfish love to forage and root around in substrate, and gravel is very well suited to this behavior. If you want to have live plants, gravel is ideal for laying down solid roots. It looks great, too, and you can mix and match a variety of colors.
Be sure to use only gravel specially packaged and sold for aquarium use. Other types of gravel could leech undesirable minerals and chemicals into your aquarium water. Also, choose gravel without sharp edges to avoid tail and fin damage.
Perhaps the most natural looking of all substrates, aquarium sand can yield beautiful results. It’s easy for fish to root through, though anecdotally some say it can irritate their gills. I am of the opinion, however, that sand is just fine for goldfish.
The downside to sand is that it’s much harder to keep clean. It’s difficult to vacuum without sucking some up, and because it’s so compacted, it doesn’t aerate as thoroughly as gravel. This can lead to trapped pockets of hydrogen sulfide that, if they release into the water, are extremely toxic. Your best bet is to stir up the sand immediately before cleaning to aerate and release any trapped gasses.
As with gravel, only use packaged sand especially for aquariums. You might be tempted to save some money and use sand from a nearby beach or leftover play sand from a child’s sandbox, but both of these pose serious potential threats to the health of your fish.
Ultimately, the great substrate debate comes down to a matter of personal preference. I’ll give gravel a slight edge, but you can’t go wrong either way.
Does My Goldfish Tank Need a Filter? What Type Should I Choose?
Because we’re so used to seeing goldfish in bowls, many people think they don’t require a filter. Not the case!
Goldfish are prodigious poopers. Like many species of fish (and interestingly, the platypus!) goldfish do not have stomachs. What they eat goes straight into the intestines where available nutrients are extracted and then it’s right out the backdoor. That means without a filtration system your fish will be swimming in its own waste in no time, a sure recipe for a short life.
So the answer is, yes, your goldfish needs a filter. But which type is best?
To start with, it must be a powered filter to keep up with your goldfish’s bathroom habits. From there you have two choices: internal or external.
You don’t need an advanced degree to know that an internal filter goes inside your tank. Constantly running, the filter draws water up and through a filtration medium and then expels it back into the tank.
Large particulate is trapped in the filter, and good bacteria work on breaking down harmful chemicals into something more benign. The filtered water is expelled back into the tank, and all you need to do is occasionally rinse out and/or replace the filter medium.
Internal filters are practical in that there’s nothing outside your tank except the power cord. This allows your tank to occupy the minimum possible footprint. On the downside, they occupy valuable tank “real estate” and they generally look ugly. They are also limited in size and capacity.
Naturally, this type of filter operates outside the tank. Water drawn through an uptake pipe enters the filtration system where, just like in an internal filter, it goes through filtration medium (sometimes multiple kinds) and is then returned to the tank.
They take up space outside the tank, so you’ll need to leave them some room on the shelf, stand, or table, though most fish tanks stands and cabinets have space within them to keep external filters wholly hidden.
On the bright side, they have a minimal impact on the internal aesthetics of your aquarium, and it’s pretty easy to hide the pipe with plants and decorations.
If you have space, go with an external filter. They are almost invariably better at cleaning than internal models and have higher capacities for collecting waste.
Since, as we’ve said, your goldfish make a lot of waste, it’s essential to have a filter that can keep their water suitably clean. Look for a filter with a high flow rate – figure on 6-10 times the volume of water in the tank per hour. That means for your 50-gallon tank, you want a filter with a flow rate of 300-500 gallons per hour.
Water Temperature: Using Heaters and Thermometers
Goldfish can tolerate a surprisingly wide temperature range. Ideally, you want to keep the water anywhere between 65-74F (18-23C) and try to avoid survivable but undesirable extremes.
For many people, this means a heater isn’t strictly necessary since goldfish like room temperature water. If you know the ambient temperature in the room will stay within these parameters, you won’t need a heater.
If your home dips below the bottom of the range, seasonally or just because it’s always cold where you live, you will need a heater. Heaters are great for maintaining a suitable constant temperature.
Whether you do or do not need a heater, a thermometer is a must-have. This is the only way for you to be sure that water is in the right temperature range. It’s a low-cost investment and just one of the many ways to keep tabs on your goldfish’s home.
Water Quality and Parameters
If you happen to own a swimming pool, you know it’s important to maintain clean water with optimal pH, chlorine levels, and so on. And that’s just for swimming; imagine if you had to live in the water!
So it goes, there are water quality requirement for keeping healthy goldfish.
Yes, they can put up with some fairly nasty conditions. But they won’t thrive in those conditions. Here are the numbers you need to be concerned with:
- pH – 7.2-7.6
- Ammonia – 0 ppm
- Nitrite – < .25 ppm
- Nitrate – < 40 ppm
The most basic tool you’ll need for having safe water is water conditioner. This is used for de-chlorinating tap water.
Next, you’ll want a water testing kit. You can purchase test strips or reusable digital testers. Either one will tell you what you need to know about pH, chlorine, nitrites, nitrates, and hardness.
Lighting Needs for the Care of Goldfish
Try having a staring contest with a goldfish. Did you blink first? Of course you did – they don’t have eyelids!
That right there should tell you that to sleep properly, goldfish need the lights off at night. Likewise, they like it bright enough to see clearly during the day. For some people, the natural cycle of day and night may be enough to get away without installing artificial lighting.
For most, however, that’s not the case. And, even if it is, there are advantages to lighting your tank. For one thing, you can control the light/dark cycle and keep it consistent year round. If you happen to live in the north and you want to see your fish after p.m. during the winter, a light is essential!
Also, lights can really make the colors of your beautiful goldfish pop! Why relegate these dazzling golden beauties to a life of perpetual dusk when they could be shining? Not only will your fish look better, but your plants and decorations will also, too. Good lighting is one of the keys to creating a wonderful looking aquarium.
Plants and Decorations
Goldfish are curious, active fish, and they love an enriched environment. I highly recommend adding decorations for swimming through and around, and for hiding behind when they’re feeling a little shy.
Take a moment to explore anything you’re planning on putting in your tank with your fingers, first. Feel around for sharp edges that could tear your goldfish’s fins, especially if you are keeping any fancy varieties.
The same goes for plants; either use live plants or soft, silky plants and never hard plastic ones. Please click here for a list of good beginner plants highly suited for goldfish tanks.
Setting up Your Goldfish Tank
Buy the tank, fill it with water, insert fish. Right? Very wrong!
I know you’re excited to start enjoying your goldfish, but before you bring home fish, you first have to set up their home. It’s kinda like cleaning out a house and repainting it before people can move in. Only with fish, it can be a matter of life and death.
Here are the proper steps to get your tank set up and ready for moving day!
Initial Tank Preparation
No matter if it’s a used tank or brand, spanking new, the first step is always to clean it out thoroughly. You never know what kind of contaminants might be lurking inside.
A new tank probably just needs a good rinsing and a wipe down, both inside and out. Do the same for any equipment it came with that’s going to be in the water.
If you’re recycling a used tank you’ll want to do a more comprehensive job to be sure it’s inhabitable and safe. To find out how it’s done, read our complete guide to cleaning out a used fish tank.
Remember never to use any soap, detergents, or chemical cleaners inside an aquarium! Leaving behind even the tiniest bit can harm or even kill your fish.
Adding Your Substrate
No matter if you’re starting with fresh substrate or reusing old stuff, you’ll still need to rinse it before lining the bottom of the tank. For gravel, pour it a bit at a time into a colander and rinse it thoroughly and repeatedly under hot water before adding it to the tank.
PRO TIP: It’s a good idea to buy a colander especially for this purpose to avoid any possibility of cross-contamination.
Sand also needs to be rinsed, but it’s too fine for a strainer. Instead, put sand in a bucket and then add water. Slosh the sand around to rinse it and then let it settle to the bottom. Once it’s settled, you can carefully pour out the water, and then add the sand to your tank.
Installing the Filter
Now you’re ready to set up the filter. This is an essential part of your aquarium system, and it needs to be ready to roll when you add the water.
Some models can be a bit tricky to install, even with the instruction sheet. Our suggestion: try and find a YouTube video of someone assembling and firing up the same kind of filter.
If you’d prefer to read rather than watch, here’s a link to a really great article explaining how to set up five common types of aquarium filter. You’ve got this!
Warning: Never turn on a filter until the tank is full of water. Running a filter dry is an express route to a ruined filter.
Adding a Heater
If you’re going to use a heater in your goldfish tank, now is the time to install it. By placing it now, you’ll be able to add plants and other decorations to hide it easily. Most likely, you’ll position the heater somewhere towards the back of the tank. Carefully place the power cord so that the tank cover doesn’t pinch it.
Warning: As with the filter, it’s important to leave the heater off until the tank is full of water. Using a heater without water can damage the element, or in some models, can even cause the glass housing to explode.
Adding Plants and Decorations
The next best thing to finally adding your new fish is setting up the plants and décor. Placing everything while the tank is still dry makes it much easier to play with positioning until you’re satisfied.
Before anything goes in, make sure to rinse each item thoroughly. You can even scrub them with a soft brush, but do not use any soap. Soap residue is not something you want in aquarium water.
As you’re putting things in place, give some thought to the needs of your goldfish. Set up places where it can go for a little privacy and nooks and crannies for exploring. Make sure not to overcrowd the tank, however, and leave your goldfish enough room to move around freely.
Artificial plants that float or require water to stand upright may be easier to add after the water is in. This allows for more precise arrangement. You can add live plants after you’ve partially filled the tank to keep their roots moist at all times.
Adding Water and Treating it for Safety
At this stage, you’re all set to fill up your tank with water. More than likely you’ll be using tap water, which is treated to be safe for human consumption. It is not fit for fish to live in, however.
This means you’ll need to use a water conditioner (you can buy it online or at any pet or aquarium store) to neutralize chemicals like chlorine that may be present.
Unless you can run a hose to your tank, the easiest way to add water is to repeatedly fill a bucket and then pour it in. Try to pour carefully so as to disturb the substrate and decorations as little as possible.
What if I Have Well Water?
Though you might think well water is close enough to natural to be safe for your goldfish, you should still treat it with water conditioner.
Well water may contain minerals, heavy metals, and runoff pesticides that are unsuitable for fish. Even if it’s run through a filtration system before exiting your faucet, it should still be treated.
Cycling Your Tank (Aka Fishless Cycling)
There’s just one last stage before your tank is ready for fish to move in. Though you’ve cleaned the water with conditioner, the system needs to be prepped and ready to deal with the incoming fish waste by establishing colonies of helpful bacteria. This is called “cycling the tank,” or “fishless cycling”.
The key to having a healthy tank is establishing a nitrogen cycle. In a nutshell, the nitrogen cycle is the process whereby ammonia in the water, created by fish waste, is converted to somewhat less harmful nitrite by bacteria. Other bacteria then convert nitrite to nitrate, which is basically harmless. Thank you bacteria!
There are several ways to kick-start the nitrogen cycle, including using filter media from another tank that already has the right bacteria present, or merely squeezing the media into your tank. Just remember, it may take days or even weeks before the water is ready for fish.
For the complete story on how and why you need to establish a nitrogen cycle, please read our comprehensive article on how to cycle a fish tank.
Buying and Adding Your Goldfish to the Tank
The best part is here! Time to go out and choose your goldfish and bring them home. To help you make the best choice, here are some factors to consider and signs to look for.
Should I Buy Male or Female Goldfish?
Unlike with some species, like bettas, it isn’t strictly necessary to separate your goldfish by gender.
The males are unlikely to be a threat to females or each other. In terms of attractiveness, male goldfish are sometimes a bit showier than females; their bodies might be slightly smaller, but the fins are often larger.
It can be extremely difficult to tell males and females apart, even for experienced aquarists. The easiest way to determine gender is to wait for breeding season. This happens naturally during the spring, but the conditions can be artificially created in a tank to force breeding.
Males will start to show breeding tubercles along their gill covers and by the pectoral fins. The tubercles look like small white dots and are quite distinct.
Outside of breeding, or spawning season, you may be able to recognize a male goldfish by a large ridge running from the back of the pelvic fins to the vent. The vent is the opening through which males release sperm and females release eggs.
Ultimately, it doesn’t really matter whether your goldfish are male or female unless you plan to breed them. Ask at your aquarium store for help selecting the gender of your choice. Even if you do get a mix, however, it may not lead to unwanted babies. They won’t breed unless the conditions are just right.
How Many Goldfish Can I Keep?
Goldfish are social fish and will thrive in the company of others of their own kind. How many you can keep at once is only limited by the size of your aquarium. Remember the rules we gave earlier?
Make sure not to keep a mix of single tail varieties and fancy goldfish in the same tank. The single tails are more aggressive, perhaps from being genetically closer to their wild relatives, and will out-compete the fancies for food.
Making Sure You Pick Healthy Fish
Buying a fish and bringing it home, only to have it die within a short time is very frustrating. This is especially true when you know you did everything right with your tank. Often what happens is the fish came home sick. Starting with a healthy goldfish can save you from disappointment.
For your best odds at choosing a healthy fish go to a breeder or an aquarium store rather than a pet store. From there, it’s all about observing the fish for certain tell-tale signs of sickness.
First, look at the conditions of the tank. Is it dirty? Overcrowded? Are there dead fish that haven’t been removed? These are all indicators that the environment isn’t healthy, and therefore the fish may not be either.
Physical signs of an ailing goldfish include torn fins, swollen eyes, white spots, clamped fins, and lethargy. You want to choose ones that are bright and shiny, and swimming around upright at a comfortable pace.
Adding Your Goldfish to the Tank
At long last, we’ve reached the moment you’ve been working towards! The tank is ready, and your healthy fish are home. Time to move them in!
Hold up there, cowboy – you can’t just open the gate (or bag, in this case) and set them loose. You run the risk of shocking your new fish and adding any contaminants that hitched a ride from the aquarium store. I’m pretty sure this is how I once ended up with snails without buying any.
Here’s a summary of the steps to follow when you’re adding new goldfish to a tank:
- Switch off the aquarium lights (the fish will be too close)
- Float the sealed bag in the aquarium for 10-15 minutes
- Open the bag and roll down from the top several times
- Scoop or otherwise drain 1/4 of the water from the bag
- Using a clean cup, add a small amount of aquarium water to the bag
- Continue adding water every 5-10 minutes for 1 hour
- Carefully capture your goldfish with a net and gently place it in the tank
- NEVER POUR THE BAG WATER INTO THE TANK
Moving your goldfish to their new home correctly is a crucial step. To learn more about how it should be done, we highly recommend reading our complete guide to introducing new fish to an aquarium.
Food and Feeding
Feeding goldfish is more complicated than simply dumping in some flakes and hoping for the best. It’s important to know what an appropriate diet is and to understand how they eat.
Are they herbivores or carnivores? Bottom feeders or surface feeders? Read on for the answers!
What do They Eat?
One of the reasons goldfish are such hardy survivors is they’ll eat just about anything. Like us, they are omnivorous creatures, meaning they’ll eat both meat and vegetables to have a balanced diet. And, like some of us, they are voracious eaters, too!
The easiest way to ensure they get the proper nutrients is to feed them specially formulated flakes for goldfish. Once the flakes hit the surface, they’ll come rushing up to get them. Flakes that sink will also be found and gobbled up if they’re still hungry.
You can also try pellets for goldfish. Since they sink, they’re perfect, because they enjoy rooting around the bottom looking for food.
As far as treats go, they will happily munch on anything from brine shrimp to bloodworms. You can also give them leafy green vegetables like kale, chard, and spinach, as well as broccoli, corn, shelled peas, and cucumber.
For fruit, you can offer watermelon, orange, and peeled grapes. Make sure to remove uneaten portions after a couple of hours to avoid fouling your tank. Treats should be restricted to just 1 or 2 times a week.
Since they’re indiscriminate eaters, take advantage of that to enhance both the health of your goldfish and their lifestyle. Vary their diet rather than sticking to a single food source. Not only will this provide a variety of nutrients, but it will also make life more interesting for your goldfish.
How Often Should You Feed Goldfish?
In the wild, goldfish eat a lot, but they burn it all off since they’re so active. Your average aquarium dweller though is somewhat more sedentary, so he or she requires fewer calories.
Feed your goldfish 2 or 3 times a day, but only small quantities. A good rule of thumb is to offer as much food as can be eaten in about two minutes. More than that and you risk either overfeeding your fish or polluting the tank with rotting food.
If you’re not home during the day, you might want to invest in an automatic fish feeder to be sure your tank buddies are fed on a schedule and are given the right amount.
Maintenance – Daily, Weekly and Monthly Tasks in the Care of a Goldfish
Nothing worth having comes without a bit of work! Here are the tasks you can expect to perform on a regular basis to keep your goldfish healthy and happy.
- Feed your goldfish (2-3 times)
- Make sure everything is being eaten to avoid waste build-up
- Inspect heaters, lights, pumps, and filters for functionality
- Monitor the water temperature to be sure it’s between 65-74F (18-23C)
- Look for signs of stress or disease
- Abnormal behavior like erratic swimming or scratching themselves on rocks and decorations
- Check fins for damage
- Look for white spots or fungal growths
- Test water for pH, bacteria, nitrites, etc.
- Use a vacuum to remove waste from substrate (this may vary – it might need cleaning more or less often)
- Replace 20% – 40% of the water
- Clean your filters and replace the media
- Trim any live plants getting too big
- Remove and clean all decorations, artificial plants, rocks, etc.
- Scrape or wipe excess algae from walls
- Wipe clean lighting covers (algae and hard water scale build up over time)
- Review food, medicine, test kits, etc. for expiration dates and throw out anything expired
Goldfish Tank Mates and Compatibility With Other Fish
Goldfish are generally sociable fish that get along, or will at least not bother many other types of fish. However, as we said before, do not mix single tails with fancies.
Aggressive species of fish should be avoided, like bettas and cichlids. This is especially true if you’re keeping fancy varieties; those big, beautiful tails are easy targets for fish that like to nip.
Here are a few species of aquarium fish that make ideal tankmates for goldfish. It’s by no means a complete list, but it’s a good place from which to start.
- Rosy Barb
- White Cloud Mountain Minnow
- Weather Loach (or Dojo Loach)
- Zebra Danio
- Apple Snail
- Ghost Shrimp/Red Cherry Shrimp
- African Dwarf Frog
Remember, there’s more to it than just social compatibility. Goldfish prefer cooler water than many tropical fish. So, while a breed of fish might be marked at the aquarium store as “community” fish, they also have to tolerate the same water conditions.
If you’ve only ever thought of goldfish as a short-lived creature bought for kids or won at fairs and then deposited in a bowl at home, this article may have been an eye-opener for you.
The truth is, goldfish, clichéd though they may be, are beautiful fish and can be very fulfilling for aquarists of any skill level. We hope that this is the start of a long and wonderful relationship.
Maybe you know someone thinking about bringing home a goldfish, or someone who already has one, but is unknowingly not taking proper care of it? Do them and their fish a favor – send them the link to this article. The more owners who know what it really takes to care for a goldfish properly, the better.
Thanks, as always, for hanging out with us today. Hopefully we’ve answered all your burning goldfish questions. If we haven’t, please take a minute to fill out our handy contact form or send us an email with your questions or comments. We will do our best to get you an answer in a timely manner!
Until next time, happy fish keeping!
External Resources on Goldfish Care
Recommended site no. 1: Is good for general aquarium set-up and on-going care, with lots of short yet information packed articles: ThatPetPlace.com: Aquatic Articles
Recommended site no. 2: We recommend for it’s short but information rich articles. Not great if looking for in-depth information, but good for beginners getting a handle on things. After reading an article, look at the links in the sidebars for a selection of related subjects: Pets.Thenest.com: Beginners Guide to Caring For Goldfish
Recommended site no. 3: We recommend because it has lots of fantastic information on types and their individual care requirements, common diseases and cures, tank set-up and more besides on goldfish keeping: Goldfish2Care4.com: Sitemap