7 Reasons Why Goldfish Aren’t Good For Beginners

Goldfish are one of the most common fish that beginner aquarists start with, but you might be surprised to learn that they’re also one of the trickiest.
Far from being low maintenance and easy to take care of, they are quite sensitive and they need specialised care.
Many goldfish never receive this care. They’re given away in plastic bags at school fairs and carnivals, housed in tiny tanks, tipped into ponds without proper conditions, overfed and under-oxygenated. Often they suffer, and die much earlier than they should.
Does this sound fair?
Of course not. As a responsible aquarist, you’ll want to understand exactly what the common mistakes are and how you can avoid them.
In this article, we’ll explore 7 reasons why goldfish aren’t good for beginners. By the end, you should have a good understanding of what it takes to care of them properly.

– 1 –
They grow much bigger than you might think

While goldfish start out small, they can actually grow to at least 6 – 8 inches or even twice that as adults if the conditions are right.

Most who live in bowls don’t live a good quality life, and they tend to die early. There’s not enough space for them to grow properly, and they also need much more water and oxygen than a bowl can provide.

So while you may think your goldfish will fit in a fishbowl just fine, the truth is that this isn’t the best environment. Put yourself in their shoes (ok they don’t wear shoes, but go with me here for a minute) – would you want to live in a tiny, cramped room where you didn’t have room to grow? No, and your fish doesn’t want to either.

They really should be kept in a big indoor tank or a large pond outdoors. So, if your goal is a happy, healthy goldfish – and it SHOULD be! – ditch the bowl. A properly-sized and filtered aquarium will give your goldfish a much bigger smile.

– 2 –
They need more oxygen than other species

Just as your goldfish needs much more space than you might have thought, they also need much more water and oxygen. In small tanks – or fishbowls – without enough oxygen, they will suffer and die, often within just a few months.

As a responsible owner, you shouldn’t let this happen. Goldfish can live more than 10 years and often up to 20 if they’re cared for properly. The oldest goldfish in the world lived until the ripe old age of 43!

How much oxygen do they need? Well, they get their oxygen from the water surface. This means their tank needs to have enough water surface area to support them properly. Multiply your tank’s length by its depth to calculate the surface area, and remember that for every inch of fish length, you need 30 square inches of surface area. Remember that your fish is going to get bigger with time!

And the water needs to move to distribute the oxygen properly. You can add airstones and pumps that provide a steady flow of bubbles to keep the water moving

Do goldfish need aquatic plants?

You can certainly add oxygen-producing plants to your aquarium, but they won’t do the job on their own.

Plants certainly add oxygen into the water during the day, but at night they take it out and produce carbon dioxide. Plus, goldfish are omnivores. They love to nibble on aquatic plants and uproot them so you might find yourself having to buy new plants very frequently. Pondweed and duckweed are good options.

– 3 –
Goldfish are messy fish

Goldfish swimming in clean water with bubbles.

Goldfish excrete lots more waste than other species, and this can quickly pollute even a large tank. Ammonia levels from goldfish waste can build up quickly and cause your fish lots of problems – include disease and even death.

To complicate things, they also love clean water. Clean water combined with messy fish? That’s not a match made in heaven. You’ll need to ensure your tank has a powerful filter (try internal, external or gravel filters). Choose a filter that has a turnover of at least six times the aquarium volume.

You’ll also need to do regular water changes to keep everything fresh. A good rule of thumb is a weekly 25% water change. Don’t use water straight from the tap – it has chlorine and other chemical nasties in it that can hurt your fish. Make sure you add a water conditioner or dechlorinator first.

– 4 –
Coldwater fish

Goldfish are coldwater fish. And coldwater fish can’t be mixed with tropical fish for a variety of reasons

Firstly, they like different kinds of water:

  • They thrive at room temperature (water temperature of around 18C) and can’t handle long periods over 25C or 77F. They don’t need a water heater of any kind, and you should make sure your tank doesn’t get direct sunlight during the day. If you try to keep your goldfish at warmer temperatures they’ll become distressed, and they’re also likely to suffer from more diseases than they would in cold water

  • Tropical fish like warmer water, and if you try to keep them in the same water as goldfish they’ll become sluggish and stop eating.

Goldfish are not very territorial, while tropical fish can be more active and aggressive – some of them love to nip on long flowing goldfish fins, for example. They can also gang up on goldfish to bully them!

Last but not least, tropical fish are faster feeders than goldfish too, so they can hog all the food and your slower goldfish might go hungry regularly.

– 5 –
They like company

Koi and goldfish thrive in social settings, their mutual company adding a touch of vibrant beauty to ponds and aquariums alike.

Goldfish are social creatures – they live in groups in the wild – so keeping two or more goldfish together is a good way of enriching your pet’s lives.

Be aware though, that when you have more than one goldfish in a tank, all the other considerations are magnified – waste, oxygen, feeding, filtration. Your tank needs to be big enough – a minimum of 15 gallons is a good recommendation – and the filter/aeration issues are even more important.

Can you put ordinary and fancy goldfish together? Not really. It might be tempting to stock a variety of different goldfish – they’re so varied and beautiful – but it’s usually best to keep like with like, in order to avoid the potential for disease and other issues that can occur.

– 6 –
They need specialist food

Goldfish are the Labradors of the aquatic world, and they’ll eat themselves to death if you give them the chance.

So be careful – if there is any food left in the water after a few minutes, you’ve given them too much – scoop it out so that it doesn’t pollute the water, and try a little less next time.

They also have sensitive digestive systems, and not all fish food is good for them. They’ll thrive on a dried flake or pellet food that’s specially designed to include the higher carbohydrate and fibre levels they need but they will also appreciate some variety in their diet.

You can treat your fish to a few squashed peas with the skins removed as well as the occasional bloodworm. Cooked rice and blanched lettuce or spinach can also be a great treat.

Check out this article to know more about goldfish food.

– 7 –
Choosing the right tank

Tank volume, surface area, filters, pumps, decoration – there are a lot of issues to consider when choosing the right tank for your goldfish.

Let’s start with size. There are lots of different recommendations so on average a good rule of thumb would be:

  • Common goldfish: 3-4 feet long and a volume of at least 15-25 gallons for one goldfish. For every extra fish in your tank, add another 12 gallons of water.

  • Fancy goldfish: 2-3 feet long and at least 20 gallons for the first fish. Add another 10 gallons for every new fish

Adequate aeration and filtration are essential for your tank – see the previous section on airstones, pumps and plants.

Make also sure you include some gravel at the bottom of the tank – it will encourage good bacteria to grow, which will reduce the levels of ammonia in the water and help keep your tank healthy.

Finally, they also like places to hide, so consider some decorations that provide a safe haven. Did you know goldfish don’t have eyelids? They’ll need somewhere to hide quickly if you suddenly turn on the lights in their room at night! But make sure these decorations don’t have pointy edges that could catch a flowing tail or bulbous eye sac.

Goldfish swimming in new aquarium with fish friends


There are a lot of important considerations when you’re deciding whether to start your aquarist hobby with goldfish – or if you’re thinking of adding some goldfish to an aquarium that’s already set up.

Consider the issues of water volume and oxygen quality. Get to know your aeration from your filtration. Get prepared for weekly water changes and other regular cleaning responsibilities.
Ensure you’ve got the right kind of food on hand – and be careful not to feed too much. Think about stocking your tank with more than just one – but not together with tropical fish!

Goldfish can be incredibly rewarding to keep, and by following the advice in this article you can help them live a long and happy life.

What do you think? Let us know if you have had a goldfish when you started and how your experience was. We would love to hear from you in the comments.