Imagine a beautiful goldfish swimming through a wonderful lake in the wild. It is a sunny summer day and the sun is shining through the surface of the water. The goldfish enjoys the day, eats plants and crumbs, he finds floating around, plays with his friends, and when the sun goes down, it will rest and go to sleep.
As a whole, a goldfish doesn´t need a light at night. A proper light source during the day is good for the sleeping patterns and eating habits of your goldfish. While a goldfish needs light to thrive during the day it also needs darkness at night to calm down and rest, just like us humans.
In nature, there is no light at night. Therefore goldfish do not need it in a tank.
Do Goldfish Need Light?
Your goldfish keeps the eyes open all the time and it seems like it does not need any sleep? In fact, goldfish have no eyelids and they sleep with their eyes wide open. But just like you and me, goldfish need time to be awake with regular feeding times and time to sleep.
Goldfish need light to be able to differentiate between daytime and nighttime. They need some kind of light source for 8-12 hours every day to be able to live a long and healthy life.
If the aquarium is in a room or place without much natural light, it is recommended to add an aquarium light.
A light should simulate day and the lack of light simulates the night, just like in nature. It should be on for 8-12 hours during the day if there are not enough natural light sources.
Can I Leave my Goldfish in the Dark?
A goldfish can survive in darkness, but isn’t it way more fun, to see your pet? Without light, a goldfish can lose its’ color and turn pale or even completely white. They need light for colorful pigmentation.
In the darkness, goldfish can lose energy, get bored or even get depressed. In order to develop a healthy eating and sleeping pattern, a regular rhythm between day and night, simulated through light, is necessary.
Is a Nightlight Bad for a Goldfish?
Too much light can be harmful, too. Goldfish need a time when they can sleep and if the light is on all the time, they can’t relax because they don’t understand when the night started.
Too much light also disturbs the balance of the aquarium. Real plants in the aquarium need the rhythm of day and night. Too much light can also cause algae to grow very fast and cloud the water, which can cause illnesses for the goldfish.
Should I Turn my Goldfishes Light Off at Night?
Goldfish do not need complete darkness at night. If you leave a small nightlight on in the room with goldfish, it won’t bother them. But any direct, and very bright light should be turned off during the night.
Do Goldfish Need Sunlight?
Goldfish in nature need sunlight as it is their only source of light. In a tank, goldfish do not necessarily need sunlight and especially no direct sunlight. Direct sunlight on the tank will warm the water, and goldfish prefer cooler temperatures.
You can place the aquarium in a room with natural sunlight, but not directly in the sun.
In nature, goldfish can always hide in deeper waters, if the sun warms up the surface, but in a tank, this is not possible.
Best Light for Goldfish
Goldfish don’t need ultraviolet light and don’t need a heating aquarium light, because they prefer cooler temperatures. Warm water does not only harm your goldfish but also disturbs the balance in your tank and can lead to fast algae growth which can ruin the water quality and harm the fish.
The light for goldfish should simulate the natural lighting in the environment. A regular cycle of day and night is essential for goldfish’s health.
A proper light source is not only beneficial for your goldfish. It also allows real plants to grow. Otherwise, you will have to go with artificial plants.
The Perfect Daylight for Your Goldfish
The easiest solution is a built-in light in the tank hood.
These lights ensure an even spread of the light in the tank and the hood makes sure, that goldfish can’t jump out of the water. A light with a timer makes it easy to maintain the perfect daytime and nighttime routines.
With real plants in the tank, you might be interested in LED lights with photosynthetically active radiation (PAR).
These lights encourage photosynthesis and thereby the growth of your plants.
Lights for the Night
You can buy lights, which are promoted as moonlights, that can be left on during the night. Sometimes these lights already come with the tank.
Beware of these so-called moonlights. Often they are blue LEDs that seem less bright than the daylight option, but they are still bright enough to keep the fish awake.
The plants will also continue to photosynthesize and algae will continuously grow. If you want to have some ambiance in the fish tank, you can switch to this moonlight setting, but you should turn it off during the night to give your fish some rest.
The lights are fancy to look at but do not simulate real moonlight.
Lisa is one of the two founders of Animal-Knowledge. She has been very interested in animals and insects from a very young age and has owned different kinds of pets such as snails, ants, fish, turtles, mice, rats, hamsters, rabbits, a dog, … you get the idea 🙂