Goldfish Care Guide
Updated: Apr 24
For a long time the common goldfish has been one of the first fish species to be kept as a pet by humans. In fact according to World Atlas, the goldfish is the most owned pet in the US! Over the pond in the UK, pet fish are the third most common pet, with the favourite being a really close battle between cats and dogs, according to Pet Plan. With the Carassius Auratus (common goldfish) being the most popular fish, and one of the most popular pets overall, this aquarium species is truly deserving of the title “the people’s fish”.
Over the last thousand years, many domesticated varieties of fish have been developed by breeders. However, the iconic goldfish remains one of the most instantly recognisable species even to people who have never owned an aquarium!
They’ve long been used as an ornamental fish when teamed with a beautiful tank, however despite being one of the staples of the pet world, a lot of their needs often go overlooked.
A lot of new owners are usually parents who see the goldfish as a low maintenance pet with minimal needs and maintenance, but they actually need a basic understanding of fishkeeping and have specific needs that need to be met in order for them to thrive in your new tank.
With that said, you’re already on the first step to finding out what your new buddy needs and ensuring that your new pet fish remains happy and healthy! Here’s our guide to explain where the goldfish came from and how you can properly care for them (including tank set up, general care and their feeding requirements!)
The History of the Pet Goldfish
In modern times you can usually find goldfish in the home swimming around an aquarium, but this hasn't always been the case. In the 9th century the wild carp ancestor of the humble goldfish were kept in ponds by Buddhist monks in China, to keep them safe from predators. This was because they were really brightly coloured in golds, reds, yellows and oranges and this made them easy to spot targets in their natural habitat.
Flash forward to the 1200s and the Goldfish had become a domesticated animal and even had completely unique genetics when compared to their chi ancestors. They were indicators of wealth, seen as a status symbol and were kept outside the home in ponds.
Now onto the 1500s and now it’s a common sight (unfortunately) to see goldfish kept indoors in bowls (this is where we get the term Fishbowl from). It’s thought this bowl home started off as a way to show off the finest specimen to guests, though many goldfish are still kept outside in ponds.
Over time they started to become permanently kept inside, in their fishbowls. This was due to their inability to evade predators or compete with the faster pond mates they had outside. As time went on their bowls became bigger to house more fish until today, where we have starter tanks being sold in stores that are anywhere from 15L to 55L! We’ve come a long way in goldfish care from those little bowls a few hundred years ago.
What’s the life expectancy of a goldfish?
Many families choose to keep pet goldfish because they see it as less commitment than for example, getting a dog. Goldfish kick the bucket all the time right? While that might be the case in many households that don’t cater towards the fish correctly, this really shouldn’t be the norm as goldfish can actually live for 20 years. This is longer than a lot of dog and cat lifespans! But how do you cater for your goldfish then? Let’s start with the tank.
Tank Setup for goldfish
If you’ve heard that “Goldfish grow to fit the size of their tanks!”, we wouldn’t be surprised. This is a common myth. As a side note, we also hear that a lot about snakes. And that isn’t true either - animals may grow at a stunted rate, including goldfish, but that’s due to other factors such as not having enough clean water or not having proper care. In short, your goldfish needs a decent sized space to live, just like any other pet.
For the tank itself, we’ve already hopefully made it clear that the typical goldfish bowls you can find aren’t really that great for them, and although a few centuries ago they were kept in bowls, these bowls were actually quite big ceramic basins and were a lot roomier than the cramped desktop bowls we see today.
In terms of tank size, it’s actually quite surprising to most - a rule of thumb is that tanks should have around 20 gallons, or 90 litres per goldfish. This is because your new little pet goldilocks can grow into adulthood and be over a foot in length. Initially, having a smaller tank is fine, but getting a decent sized forever home at the start would be the easiest option for your fish.
Having a tank this size also means that you clean the water less, your filter doesn't have to work as hard to keep the water looking fresh and your fish can roam free and explore all of the plants and decorations you’ll equip the tank with.
Related: How To Set Up A Freshwater Aquarium
Now let’s chat about temperature
Goldfish can survive in waters ranging from almost freezing to temperatures you’d see more commonly in tropical tanks. However, that doesn’t mean they can endure this daily for a prolonged period. Goldfish do require a tank heater to ensure temperature stability. It needs to be set to between 20C and 22C, or around 68F. If you’re using a larger tank, this will help the tank to maintain a constant temperature. If, for example, the tank is placed in direct sunlight, smaller tanks will heat up faster and this can distress the goldfish, so consistently regulated temperatures are best.
Water quality and filtration requirements
Goldfish, poop. They poop a lot. You need a powerful aquarium filter such as a decently sized canister filter to handle the waste and you need to be attentive to their tank’s cleanliness.
The hang-on-the-back style of filters can be great for goldfish but they need to be oversized to meet the task. What you’re aiming for here is to aggressively filter the water but without creating any currents. You want to minimize the impact the flow has on your new little goldfish as a strong current can be distressing.
To help with this you can set up aeration pipes and diffusers such as a bubble wand but be careful when housing certain varieties, for example bubble-eye fishes. The aeration breaks up the current slightly to give your fish a break from swimming against it whilst also ensuring great oxygen content for the water.
In terms of pH levels, Goldfish prefer slight alkalinity opposed to acidity, so the pH you’re aiming for is between 7.0 and 7.4.
For filters, common starter filters are Under Gravel Filters, Submersible Filters and Sponge Filters (Sponge filters work with Air Pumps instead of motors, filtering and adding air at the same time, but less powerful than regular powered pumps)
For air pumps you don't need anything special for the most part. For Waster Testing kit we always recommend API's Master Test Kit. They're really accurate and will pinpoint any issues your tank is having!
Under Gravel filters such as the Penn Plax work with an air pump and they make for tidier looking fish tanks. Their benefits include being able to pull left over food through the gravel so that it can't harm your fish as it breaks down, however cleaning these filters can be a bit of a chore!
Submersible filters are the norm for many aquarium owners, they're much easier to clean and are powerful, making them excellent cleaners!
Sponge Filters work like the under gravel filters we've listed (with an air pump), however they have more perks including being easier to clean as well as giving you the option of using one of the sponges in a new tank to help cycle it faster! We also think they're pretty cool looking, and if you have small fish, shrimp or fry then they'll be safe with a sponge filter.
For Waster Test Kits we always recommend API's Master Test Kits. They're accurate and reliable, and are a necessity when cycling your tank, as well as weekly water monitoring before you do any cleaning!
Next let’s have a look at Tank Decorations
The good news here is that this is probably the simplest of sections. The tank interior doesn’t require a great deal of attention in terms of decorations. Use Pea Gravel instead of sand or fine gravel so that your fish can avoid eating it when they nibble on the food on the tank floor.
Decorations and artificial plants can add a nice looking touch and create a great aesthetic but need to be used minimally so that there’s a decent amount of swimming space. Live plants can only be used with caution. Goldfish will consume almost any plant you put in, so go for the tough or worst tasting such as anubias or java ferns.
Shopping list for decorations:
While we’re on the topic let’s dig into some food.
Your pets diet is essential to their longevity. Technically omnivorous, goldfish will eat almost anything you throw in the tank - but not all goldfish food is equal. They benefit most from a high carb to protein diet. But you don’t have to check food labels on all of your fish food - just opt for a quality food product specifically tailored to goldfish and you’ll be okay. You can even throw in some treats now and then.
But don’t overdo it. Goldfish WILL eat any food you throw in the tops of their tanks. They aren’t hungry though, they just don’t actually know when to stop eating, and feeding them too much will harm them and dirty the water. You should only feed your fish what they are able to consume in 2-3 minutes, once or twice a day.
Another tip with food is to pre-soak it. If your feeding flakes then they mostly stay on the surface of the water for quite a while before dropping down into the water. As your fish swim up to grab this food, they take in air too which throws off their swim bladder which can cause them to float upside down. To pre-soak, just put some of the tank water into a cup, place the food inside the cup and swirl it around a few times. Then just dump the water back in the tank along with the food. Don’t worry about it sinking to the bottom of the tank - as long as you’ve used the pea gravel then your fish will be able to feed from the bottom of the tank just fine.
Lastly, let’s just swim through how to add more fish to the tank.
Goldfish are nice, they’ll tolerate and even enjoy other’s company. However, you need to ensure you don’t overcrowd the tank. A 50L tank might seem fine for four goldfish in the beginning but they’ll outgrow the tank soon enough. Remember to stick to the rule above, having 20 gallons per adult fish.
Don’t add too many fish too quickly, start with one or two then gradually, if you want more, add them one by one at about monthly intervals. By doing this you get to monitor how quickly the tank’s cleanliness deteriorates. If it gets dirty too quickly then you’ll need a bigger tank and a better filtration system.
Following the above guidelines and sticking to top-shelf equipment and foods, you will find that maintaining your goldfish’s health is not as hard as you thought. In truth, if reared in an environment that meets its particular needs, your goldfish just might outlive you.
If you want to read more about goldfish, you can learn about their behaviours and what they may mean here.
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