Can Goldfish See in the Dark?

Most goldfish owners are not sure if they should keep the aquarium lights on at night. The confusion stems from several contradictory claims about goldfish’s night vision. In fact, even experts are divided on whether goldfish can see in the dark. So, what’s the truth?

Goldfish have a good eyesight but they cannot see in the dark. Alternatively, they use their superior sense of smell to swim around the aquarium at night. In addition, they are blessed with a lateral line system that helps them spot any vibration or movements in the surrounding water.

In this article, we’ll dig deeper into the topic and answer all related questions, such as how well can a goldfish see, how they navigate in the dark, and how much light and darkness they need.  So, let’s dive right in.

Can goldfish live in the dark?

While goldfish can live perfectly well in darkness, living in the dark for a long time can make them ill. In the wild, goldfish typically sleep during nighttime. However, they can also navigate in the dark and hide from predators, if required.

How do goldfish navigate in the dark?

Goldfish cannot see in the dark. However, they can still navigate in the dark, thanks to their lateral line system. So, what is the lateral line system? It is basically a system that allows goldfish to sense nearby predators from any pressure changes in the water.

How does the lateral line system of goldfish work?

Goldfish have a series of pressure-sensitive lateral organs (AKA Neuromasts) along the surface of their body. So, these organs contain sensory cells capable of detecting movements or pressure changes in the water. Goldfish use this lateral system to swim around in the water during nighttime.

How good is the eyesight of a goldfish?

Goldfish can clearly see everything around them as we humans can. In fact, goldfish have better eyesight than humans in some respect. For instance, their eyes have four color receptors, compared to only three in our eyes. In fact, the fourth receptor enables them to see ultraviolet light. However, their depth perception is not that great. In fact, they can clearly see distances of up 15 feet only. Also, human eyesight is up to 60 times sharper than a goldfish’s eyesight.

Are goldfish highly sensitive to polarized light?

Yes, goldfish are highly sensitive to polarized light. We typically see this type of light during dawn and dusk. So, that is exactly why golf in the wild usually hunt or look for preys during that time. In fact, recent studies show that polarized light can improve a goldfish’s ability to perceive contrast in an image.

Can goldfish smell and/or hear?

Well, goldfish actually have a better sense of smell than we humans have. In fact, their acute sense of smell helps them get around the water at night without bumping into other fishes or objects. Also, your fishy pet can actually hear most of the sounds that you can hear. In fact, goldfish have ears inside their head.

How long should you keep your goldfish in the dark?

In the wild, goldfish stay awake for more than 12 hours. Typically, they remain active during the daytime and sleep at night. So, you should replicate the same cycle in your aquarium. Ideally, you should keep your goldfish in the dark for around 12 hours at night.

What happens when a goldfish is left in the dark?

First of all, you should not leave your goldfish in the dark for more than 12 hours a day. In fact, prolonged darkness can slow down their pigment production. As a result, the colors on their body may start to fade. In fact, some people believe that keeping a goldfish in the dark for too long can turn it white. This theory, however, is still not proven. But it is true that lack of light can make the aquatic pets lethargic. In fact, prolonged darkness can even make them ill.

Do goldfish need light?

In the wild, goldfish live in ponds or shallow lakes where the environment is fairly bright. So, goldfish, unlike deep-water fishes, are not accustomed to living in low lighting conditions. In fact, they need adequate light to stay healthy and active.

How much light is too much for your goldfish?

Goldfish typically live in cool water. So, you don’t need to use a heat light in your aquarium. In fact, even natural lighting could be enough for your goldfish. However, if the room where you’ll keep your goldfish doesn’t get enough sunlight, you should consider using artificial lights in your aquarium. More importantly, make sure you don’t turn on the tank lights at night.

What happens if your goldfish gets too much light?

Too much light can disrupt the sleep cycle of your fish. As a result, goldfish may stop eating and start fighting with one another. In addition, excessive light could encourage faster algae growth inside the tank. This, eventually, could cloud the water and jeopardize the health of your aquatic pets.

How to deal with any algae problems in your goldfish tank?

If your goldfish tank and the water in it look cloudy or murky, it could be a sign of algae overgrowth. Typically, too much light on your goldfish tank causes algae overgrowth. So, the first thing you should do is to change the water of your tank. In addition, consider reducing the tank’s exposure to lights. Also, avoid over-feeding your aquatic pets and remove any leftover foods immediately. Usually, high phosphate and nitrate levels in the water cause faster algae growth. So, you may want to test the tank water for phosphate and nitrate levels.

Do goldfish sleep at night?

Yes, goldfish typically sleep at night. Some of them may take a short nap during the day, but they usually sleep at night. Often, they sleep for 8 to 12 hours a day.

How do goldfish sleep?

Goldfish typically need a quiet, dark place for a good night’s sleep. So, make sure you turn off all the lights and maintain a serene environment around the aquarium during the night. However, goldfish don’t remain still when they sleep. In fact, they keep swimming with their eyes open even when they sleep.

How to tell if your goldfish is sleeping

Since goldfish don’t have eyelids and they don’t lie down when they sleep, it could be difficult to tell if they are sleeping. However, there are a few ways to know this. For instance, when they sleep they usually become less active. Also, if you notice them swimming close to the bottom of the talk, it could be a sign that they are sleeping. In fact, you may even notice a slight fade in their color when they’re sleeping.

How to tell if your goldfish is sleeping or feeling sick?

If your goldfish is lying at the bottom of the tank, it is probably sick. A sleeping goldfish will float at least a few inches off the bottom. Also, notice the head of the fish. If you notice the head leaning downwards, it is typically a sign of illness. In fact, a sleeping fish never goes upside down. If you notice any signs of illness, you should consult a vet as early as possible.

What are some of the consequences of lack of sleep?

If your goldfish do not get enough sleep, they may experience several health issues. In fact, lack of sleep can slow down their metabolism. Eventually, this can weaken their immune system. As a result, they can become more prone to infectious diseases. In addition, your goldfish can feel tired due to a lack of sleep.

Is direct sunlight bad for a goldfish tank?

Ideally, the temperature of your goldfish aquarium should be anywhere between 68° to 74° F. So, it would be a good idea to avoid direct sunlight on your goldfish tank. Otherwise, the tank water can heat up quickly, making the water environment harmful for your fishy pets.

Should you use artificial lights in your goldfish aquarium?

It depends on where you put your goldfish tank. If the area is well-lit or receives enough indirect sunlight throughout the day, then artificial lights are not necessary. If, however, your goldfish tank is placed in a dark room, you should use aquarium lights. Also, if you have live plants in the tank, consider using aquarium lights to ensure their survival and growth.

How to regulate the temperature of tank water

First of all, make sure you don’t use heated lamps in your goldfish tank. Typically, the tank water does not need heating. Goldfish live well in cool water. If, however, you think you need to regulate the temperature of tank water, consider using a tank heater.

What lighting options are suitable for a goldfish tank?

You’ll find many different types of lights for your goldfish aquarium, such as fluorescent lights, incandescent lights and LED lights. Each type has its own pros and cons. However, fluorescent bulbs are ideal for the goldfish tank as they do not produce as much as heat incandescent bulbs produce.

GE Plant and Aquarium Fluorescent Light Bulb, F20T12 Grow Light, 20-Watt, 750 Lumen, 1.5-Inch Diameter, Warm White, Bi-Pin Base, 6-Pack, Grow Lights for Indoor Plants, Aquarium Light Bulbs
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GE Plant and Aquarium Fluorescent Light Bulb, F20T12 Grow Light, 20-Watt, 750 Lumen, 1.5-Inch Diameter, Warm White, Bi-Pin Base, 6-Pack, Grow Lights for Indoor Plants, Aquarium Light Bulbs
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