Do goldfish need light?

Do goldfish need light? Well, how would you like to be kept in the dark?!

Like most animals, goldfish would not be healthy if permanently kept in dark conditions.

Unlike some fish that live deep in the sea, wild goldfish live in lakes and rivers. These relatively shallow waters are often illuminated by quite bright daylight. Therefore, the lighting conditions in your aquarium should replicate this natural environment as closely as possible.

What if goldfish live in the dark?

Your fish’s color could start to fade if your tank is in a dark place. Goldfish have even been known to turn an unhealthy white color when they don’t get enough light.

Lighting changes let your fish know whether it’s currently day or night. How well your goldfish sleeps, how much they eat, and even their behavior will all be affected by a lack of light.

Can goldfish have too much light?

While it is important to make sure that your fish gets enough light, you should also make sure they don’t get too much!

For instance, you should never place a goldfish tank in direct sunlight. The heat from the sun will cause the water to heat up and the strong light will encourage the growth of algae.

Also, just like too little light could confuse your goldfish into thinking it’s always night time, too much light will make your goldfish think it’s always day. This will throw off your fish’s sleeping, eating and behavior just as badly.

Do I need an aquarium light for my goldfish tank?

If your tank is in a poorly lit area – or if you want to grow live plants, such as hornwort – then it would be a good idea to include a light in your aquarium.

Remember to switch off your aquarium light at night, as this will replicate natural day/night cycles. Like humans, goldfish prefer to sleep in the dark.

Can Goldfish See In The Dark?

No, they are not able to see in the dark. In the daytime they have fantastic sight but when the dark sets in they are similar to ourselves in that they can’t see in complete darkness.

They rely heavily on their other senses, mainly their really good sense of smell along with an ability to sense vibrations in the surrounding water.

7 thoughts on “Do goldfish need light?”

  1. Thank you for this 🙂

    I have one goldfish, approx six inches long.
    He is living in a 55 ltr. tank. I have two acquarium lights in the hood 15 Watt ea. but my fish is still losing his colour. Should he have larger wattage bulbs ? How long does it take for their colour to return.
    When I was cleaning his tank, I dropped the hood and broke the light fitting. He was a few days without his lights , but I did place a standard lamp by the side of him so that he wasn’t in the dark.
    I only give him the flakes to feed on ‘Top Fin’ Colour enhancing Goldfish Flakes – do they like anything else to eat as a treat ? Even after feeding, it is not long before he is looking for more – that is why I am sure it is a ‘he’ and not a ‘she’ !!
    Thank you…

    • Hi Pat, thanks for your comment
      we hope you and your goldfish are still doing well

      Goldfish tend to lose their colour if they become stressed, much like you or I, when we feel unwell we turn pale.

      While it isn’t good for a goldfish to be kept in complete darkness, as long as the room is lit and you can see them, this is fine, they don’t need bright lights all the time unless you want plants to grow in your tank.

      goldfish can eat all types of different foods, good treats for them include frozen bloodworms, brine shrimp, broccoli, green beans etc. we have a page full of treat suggestions for goldfish here:

      we would also recommend if you haven’t already to upgrade your tank size if possible, 55 litres is quite cramped for a 6″ goldfish.

      hope this information helps 🙂

  2. Can I use artificial light to enable my outdoor, pond goldfish to keep healthy. They have been in the house shade for 2.5 months since I’ve been at this address. One, about 12cm long died after swimming on its side a few weeks ago. I had 10 baby fish about 1.5cm long and I think some of them have gone. Now my largest one, 4 to 5 years old and around 15cm long is on his side. You mentioned the fish needing light and I’m considering that this may be th problem. Please help me if you can.

    • Hi Judy, thanks for your comment
      we hope you were able to figure out what was causing the problem, and sorry to hear that you lost some of your fish.

      While it is true that goldfish need light, a lack of it will not kill them, it is likely that something else has caused them to die, we recommend testing the water to see if there is something wrong, or assessing the situation.

      The goldfish could’ve died from temperature shock, stress, disease etc. It is hard to pinpoint, but it wont be the lack of light.

      If you want to though, you certainly can add artificial lighting to your pond, just make sure the electrics are secure and in a watertight seal.

      hope this helps 🙂

  3. My aquarium light just finally decided to give up. What can I use to substitute while I’m waiting for a new light to come in?

    • Hi Mari,

      Any lights should do just fine, and unless you have live plants then you don’t need to worry about your fish being in darkness for a while.

  4. Hi, my tank is right in front an exact-north-facing window. I open the curtains so it is very bright but never any direct sun. Do I need the led lights? Mine is a 6 led light strand, mounted to the tank lid. I thought that the extra light isn’t necessary, what do you think?

    Also, the tank is on a credenza but right below it to the side (between the window and credenza ) is the air vent. In winter it blows warm air up right by the glass of the tank. Is that ok? I also have an automatic tank warmer in there, so I guess if it gets too warm it turns off.


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