Want to learn how to take care of a goldfish?
You’ve come to the right place.
This is THE best guide to goldfish care 101 on the planet.
If you’re an overwhelmed beginner wanting someone to show you the ropes, you’ll love this guide.
Now you can start building a healthy goldfish community despite having:
Zero pet sitting jobs.
Zero goldfish-savvy connections.
Zero experience keeping fish.
I’m going to walk you through the basic steps you need to take to save your new goldfish from total disaster.
1. Choosing your New Goldfish
I think you’ll agree with me when I say:
The funnest part of goldfish keeping is getting new fish!
You’ll want to pick out a fish that you not only fall in love with at first sight, but is healthy to start with.
Unless you have solid nursing skills it takes to revive a sick fish (which is definitely NOT an easy thing to do), I recommend getting off on the best foot possible by purchasing a fish that isn’t obviously unwell.
(Note: if you already have purchased your goldfish, then you are already in knee-deep and you can skip this step and move on to the next point.)
If you’re shopping at your local pet store, you’ll want to look for fish that meets the following criteria:
- Swims around actively and normally (no floating or sinking problems)
- Looks perky and is constantly on the move, trying to find something to munch on
- Doesn’t have severe genetic defects like a collapsed mouth, bent back or missing anal fins
- Isn’t in the same tank with sick or dead fish that can transmit disease
- Isn’t living in dirty water conditions (that could lead to infection)
- Doesn’t show obvious signs of illness (bloody looking fins, white spots, red marks, etc.)
But here’s something else to be aware of…
The kind of goldfish you get can make a HUGE difference in the size of tank you will need in order to let it grow to its full potential.
Slim-bodied goldfish like Commons, Comets and Shubunkins may start out small (they are usually sold as very young fish), but grow to be around a foot long. This is why they are commonly kept in ponds.
So if you’re tight on space, a fancy goldfish is probably a better fit for you.
(Fancy goldfish are the kinds with two tails and a shorter body, and they don’t get nearly as big so they don’t require quite as much room).
Once you have chosen your new finned friend, it’s time to take it home and do some quarantine!
2. Quarantining to Rest & Treat Your Fish
Regardless of where you bought your fish from, all fish need to be quarantined. Quarantining is when you put the fish in a separate tank (preferably cycled) for a time before introducing them to your main tank.
Why exactly would you want to do that?
- Quarantine is giving your new fish a period of time to “rest up” in a separate area before being introduced to your other fish. (If you don’t have any other fish already, you don’t have to do this in a separate tank). That way they don’t catch anything from your existing fish while they are stressed after shipping. Their immune systems will be really low right now, making them prone to illness.
- Quarantine allows you to treat for all the common goldfish diseases your fish might have to help prevent them from coming down sick later. (If your supplier has already fully quarantined their fish – and I mean FULLY, including using microscopy techniques, then you don’t have to treat for all the diseases.) You can learn the best combination of medications you can use that are proven to eradicate ALL common goldfish diseases (and what order to use them in) in my book, The Truth About Goldfish.
This is crazy:
Nearly all pet store goldfish are already sick or are on the verge of sickness.
The pet stores can’t afford to quarantine each shipment of fish for weeks and treat them for the host of diseases they are carrying before offering them for sale. So all they do is ship ’em in and ship ’em out.
They may look good now, but they have been passed through many stations and very stressed by the time they’ve arrived at their final destination. By the time they get home, they’re all but spent and are harboring a host of pathogens invisible to the naked eye.
These pathogens may not cause any problems to begin with – but as they multiply to out-of-control levels, the fish eventually succumbs.
That’s why it’s so common to hear,
“My goldfish are ALWAYS DYING!”
To recap, if you get your fish from a pet store, you are going to need to treat your new fish for disease yourself. And if you already have fish, you are going to need a separate tank to do this in so your new fish doesn’t contaminate the others. Do otherwise at your own risk.
3. Getting Your First-Time Aquarium Supplies
How you set up your aquarium will have a HUGE impact on your success as a goldfish keeper.
You’re probably wondering:
“Can I keep my goldfish in a bowl?”
Sorry, but bowls are out of the question. You can read why here. (Don’t worry, I’ll wait.)Are you back? Great!
The bottom line?
A good tip when choosing a goldfish tank is to get the biggest tank you can afford.
A bigger tank = healthier fish.
Healthier fish = happier owner.
That depends on the goldfish – and how many you want to keep.
Slender, single-tailed goldfish varieties grow so large that they need 40 gallons for the first fish, 20 for each additional one.
I know, it’s hard to believe they can start off so small and end up so huge.
Fancy goldfish (the ones with short bodies and double tails) can reach 6 to 8 inches, so 10 to 20 gallons per fish is the rule of thumb. Their size makes them much better suited to indoor aquariums.
But you’ll need more than a tank to have a thriving goldfish…
- Filters provide a place for beneficial bacteria to grow on that keep your water quality in good shape for longer. The beneficial bacteria are what help to keep your water safe. You will still need to perform water changes even if you have a filter though.
- For water changes, you will need a siphon. The kind that connects to the sink are great for tanks above 20 gallons and will save you lots of back pain from hauling buckets. No matter how great your filter is, you will always have to do some level of water changes.
- A heater keeps the temperature steady, preventing changes that can stress your fish. Especially recommended for fancy goldfish.
- An aquarium light will keep your fish and plants thriving (as well as show them off).
There are also some other things that can make your tank a better home for your fish (after all, the more interesting you make their environment the better):
- A sand substrate is a much safer alternative to gravel (NEVER use aquarium gravel with goldfish – it is a choking hazard for them). Sand gives something for the fish to forage in and makes the tank look nice without adding the risk of choking.
- Bubble walls are also nice for increasing oxygen and adding some sparkle to the back of your tank. They require an air pump and airline tubing to work. Certain kinds of filters do not oxygenate the water much, so supplementing with an airstone can be very beneficial.
- Live plants beautify your tank and provide safe hiding places for your fish (many decorations can be dangerous to goldfish as they can leach contaminants in the water and goldfish can get stuck in them). Be sure to get plants that are goldfish-friendly or you will have just purchased a very expensive salad for your fish!
How do you set this all up?
You can learn everything you need to have for a fully functional aquarium in this ultimate goldfish tank guide.
It will get you off to a fantastic start!
Now that you know about properly setting up your aquarium, give yourself a high-five (and move on to step 4).
4. Adding the Right Water Conditioners
So you have everything set up and running now.
Placed your tank? Check.
Hooked up filter? Check.
Added water to tank? Check.
You’re not ready to add your new fish yet.
Your water (if it is from the tap) contains chlorine and chloromines, which will burn your fish alive.
This has to be removed using a water conditioner. I like Prime because it also cuts the toxicity of ammonia and nitrite for 48 hours, two parameters that are very prevalent in new aquariums.
But even once you add your water conditioner, there’s still something else you need to know…
A Word of Caution:
At this point in the process, many people will wait 20 minutes (or 24 hours, depending on what the pet store employee has told them) and then put goldfish in. Who wants to wait, right? But within a week or so, their fish is seriously ill – maybe even dead.
This is because they did not cycle the tank first… … or they did not do enough water changes to compensate for the lack of an established filter.
Let me explain:
Goldfish produce waste which quickly becomes toxic to them. Only two things can detoxify or remove it: water changes or a colony of good bacteria. Beneficial bacteria can help convert this waste into non-toxic forms through a process called the Nitrogen Cycle.
Something called a ‘fishless cycle’ is done before adding any fish to build up a colony of good bacteria.
If you have fish already, it’s too late to go through this process. Expect to be doing very frequent water changes and supplement with a beneficial filter starter bacteria culture (this speeds up the process) at least every other day for a few weeks until the colony gets established in your filter. (But an established filter won’t ever do ALL the work for you – it just cuts it down some.)
Now that you know your water will be safe for your new pet, it’s time to add fish!
5. Acclimate Your Goldfish to their Aquarium
Now that you’ve got your beautiful new goldfish, here’s how you introduce him, her or them into the tank.
Float the bag in the water for 20 minutes to match the temperature.
Open the bag. (Please DON’T dump the yucky water from the bag into the tank.)
Using clean hands, gently scoop up the fish and transfer it into the aquarium.
There you go!
It’s common for new fish to hide at the bottom for a bit as they adjust to their new surroundings.
They might just be a little skittish for a time. But they’ll perk up after a bit.
If your fish have recently been shipped, you’ll want to make sure you don’t feed for 24 hours. Once you start feeding, feed very sparingly to avoid causing water quality problems.
Which brings us to the next point…
6. Properly Feeding your New Pet
Feeding your goldfish is a SUPER important aspect of goldfish care.
First (and most obviously), goldfish need food at regular intervals to survive.
But more importantly, how much you feed affects your water quality and your fish directly.
A healthy diet = a healthy fish.
But the problem is that there is a lot of confusing information out there on exactly what is the proper way to feed.
Which is why I put together a complete guide on goldfish food.
Then you’ll know exactly what and how to feed your fish, setting you up for success.
Overfeeding is a serious killer of goldfish. And it’s hard because goldfish love to eat… and eat…
But I address how to deal with this in the most safe way possible, while ensuring your fish doesn’t feel bored or hungry all the time.
Some goldfish foods are just a bad idea no matter what.
Take commercial flakes, for example.
As soon as they hit the water, flakes start leaching their ingredients, which can lead to water quality issues.
The fish also end up ingesting a lot of air as they eat them – but the main problem is the low quality ingredients they contain.
… A goldfish floating around from constipation.
Get a high quality goldfish food instead. (Hint: cheaper is rarely better.)
Pellets or gel food provides all of the nutrients goldfish need, AND they are digestible.
The best ones have lots of protein, fat, and very little fiber. The sinking kind of pellets are ideal.
But here’s the catcher:
No matter what you buy, processed foods (which are very rich) can’t make up a complete goldfish diet.
It would be like a person eating a cheeseburger every meal!
He’d be sick and overweight.
Fibrous veggies should actually make up the majority of their meals.
That’s why lettuce, spinach and kale are great ways to go.
So check out the feeding guide and then come back to read step number 7!
7. Caring for Goldfish: Water Changes for a Healthy Fish
Wouldn’t it be great if goldfish keeping was a one-time, “set-it-and-forget-it” thing?
Well, the truth is that there’s more to it than setting up a tank, adding fish and putting some food in every so often.
See, just like cats need their litter boxes changed…
… goldfish need their water changed.
On a regular basis.
This is because the filter converts poisons in the water into a somewhat safer substance (nitrate), but it can’t totally get rid of that substance.
That substance will just build up and build up until it starts harming your goldfish.
Replacing a percentage of your tank’s water with fresh, clean water regularly.
You can do this with an aquarium siphon.
Now, exactly how much and how often depends on your stocking densities in your tank, the amount you feed and your water test results (if your nitrate levels are over 30, you might not be changing enough water often enough).
Last but not least:
Keeping an eye on your fish is important to make sure that there are no weird things going on with them.
Pay attention to how they are swimming, where they are spending their time in the tank, and how they look.
Fortunately, watching your goldfish is fun and enjoyable! (That’s why we keep them, after all.)
Whenever you notice a change in appearance or behavior, do a water change.
A day shouldn’t go by where you don’t check on them, because sometimes a lot can change in a short period of time.
8. Testing Your Water for the Critical Parameters
Regularly testing your tank’s water is a big part of taking care of your fish, ensuring that their environment stays safe for them.
Poor water quality is a HUGE killer of aquarium fish, but the problem is that the water may look just fine. It doesn’t have to look cloudy or gross to be extremely toxic to your fish.
That’s why we use test kits.
Test kits are the only way to know what’s going on with your water.
After you add fish, your water quality changes over time. By testing the water periodically, you can ensure that nothing gets out of control before it is too late.
It is recommended to test your water every single week in an established aquarium (one that has been set up longer than 1 month).
The biggest levels to check are ammonia, nitrite, nitrate, pH, KH and GH levels to make sure they are within recommended ranges.
It’s a good idea to check your pH every day. That’s because the pH can suddenly dip without warning (called a pH crash), leaving your entire tank wiped out.
I use a pH and ammonia alert combo pack in my tank to keep an eye on things without having to test the water daily (a pain). All I have to do is look at it when I feed the fish.
9. Identifying and Treating Disease Problems
Goldfish are living creatures, and sometimes they can get sick.
It can happen because of their environmental conditions being less than optimal.
It can happen if you added a new fish without quarantining them, infecting the others.
It can even happen for no explained reason (often because the fish brought something in with it to start).
I get it:
Dealing with disease is something most fish keepers have to face at some point.
Even though it’s not fun, sometimes it’s a part of the package.
But good news:
The sooner you catch something, the better the chances are that you will be able to help turn things around. Being able to recognize when something is different about your fish QUICKLY can make or break its prognosis.
Check out our article on goldfish disease for more information on abnormal symptoms so you know what to look for.
Now it’s Up to You…
It would be great if there was an autopilot setting for taking care of a goldfish.
That way you could just set everything up, kick back and relax.
But when it comes to pet ownership, you’re totally at the wheel.
Your care (or lack of care) will determine – in a large part – whether they live or die.
The bottom line?
They NEED you.
Their lives are in your hands.
You are the one who determines how clean their water is, how crowded they are, if they have enough food, and what to do when they are sick.
So, you have some responsibilities to tend to if you want your goldfish to thrive.
If you want to become a great goldfish owner, I recommend checking out my book The Truth About Goldfish.
It covers ALL the aspects of goldfish care for advanced an beginning goldfish keepers alike.
Thanks for reading this care sheet, and I’d love to hear from you in the comments section below if you want to drop me a line.