Do Guppies Need Light?

Just like humans, guppies rely on their circadian rhythms to tell between night and day. A dark environment at night and light during the daytime, whether it be natural or artificial, is vital for your guppies’ health and well-being. 

The rest of this article will tell you all you need to know about guppies and their needs regarding light.

Why Do Guppies Need Light? 

Like most animals, fish depend on light cycles to distinguish day from night. Despite being in an artificial environment (i.e. a freshwater aquarium), their biological needs don’t change. They rely on their circadian rhythms and require rest at night and activity during the day.

How Much Light Do My Guppies Need? 

Aquarium experts advise giving your guppies 8 – 10 hours of light each day. However, some sources – like – suggest between 12 – 16 hours. If you are unsure, it’s best to mimic a natural daytime light cycle as much as possible, which can differ depending on the time of year.

Too much or too little light will weaken your guppies’ immune systems and make them susceptible to disease and death. Just like humans, guppies need regular rest, and you should turn the lights off during the night so your guppies can get enough sleep.

Aside from sleeping, guppies also breed during the nighttime hours, and light during the nighttime can inhibit their natural breeding patterns and stress your guppies.

If your lights don’t have a timer included, we recommend buying a light timer so you can set to automatically dim or brighten your artificial aquarium lights. This helps ensure your guppies aren’t getting too much or too little light.

Guppies in freshwater aquarium

Natural Vs. Artificial Light: Does it Matter? 

While there is some debate on this issue, some experts state that sunlight is healthier for guppies, helping adults and fry grow larger and develop more vibrant colors. The pro-sunlight experts also explain that direct sunlight fosters algae growth in the tank, which provides a natural food source. Regarding guppy fry, studies have shown that they grow bigger and faster when exposed to natural sunlight.

However, too much direct sunlight is harmful to your guppies, as it can overheat the water and kill the fish.

If your aquarium is in a room with adequate natural light, such as a living area with plenty of windows, you may not need to worry about adding artificial light to your tank. While natural light is the best option for your guppies, experts haven’t found any significant evidence to discourage artificial lights – just make sure you’re able to replicate a regular and consistent light cycle.

You can use LED or fluorescent lights in your aquarium. LED lights use far less electricity than fluorescent bulbs, and the color settings are easier to adjust. They also don’t run the risk of heating your tank and harming your fish.

LED lights are far more versatile than fluorescents and come with a variety of settings such as dimming, programming color settings, and (in some models) smart systems that automatically dim or shut off the lights.

How Do I Tell If My Guppies Are Getting Enough Light? 

Experts recommend buying an automatic timer for your lights, that way you won’t have to worry about how many hours your guppies are getting per day. However, if you’re unable to obtain an automatic timer, there are some key ways of knowing whether your guppies are getting enough light.

Below is a list of abnormalities to look for, according to, which can be attributed to a number of unhealthy tank conditions, including too much or too little light:

  • Discolored scales
  • Scales that don’t look smooth
  • Bumps or abnormal growths (especially in fry as they grow bigger)
  • Cloudy and/or bulging eyes
  • Too slow or too rapid breathing
  • The fish are sluggish or lethargic, with little to no active swimming
  • Poor appetite
  • Hiding

While many of these abnormalities directly result from bacteria or parasites, too much or not enough light weakens guppies’ immune systems, making them susceptible to disease.

What Color Light is Best? 

The full RBG (Red, Blue, Green) spectrum is the highest recommended for freshwater aquariums in general. One of the main reasons is that it inhibits the growth of algae, which means less time spend cleaning your fish tank. The full RBG spectrum also brings out the vibrant colors of your fish and plants.

However, 8000K white is also recommended because this light most closely mimics the shallow water conditions in which guppies thrive in the wild, according to the aquarium supplies manufacturers at Current USA.

This light is on the warmer end of the spectrum and helps bring out the vibrant colors of your guppies.

An added bonus is that this light also helps your live plants thrive (especially plants that grow best in low and medium light), and healthier plants inside the aquarium make for the ideal environment for your guppies.

What Color Light Do Guppies Like Best? 

While there is no evidence to suggest that guppies have preference for any particular kind or color light, their health is the best indicator of whether they are happy. The experts at point out how blue light may be specifically beneficial to guppy fry, helping them develop more robustly from fry to adult than other kinds of light.

Guppy Fry: What are Their Light Needs? 

Low light is believed to reduce stress in pregnant guppies about to give birth. However, once the fry are born, they thrive in well-lit environments, and will need a few hours more light per day than adult guppies. While your guppy adults need 8 – 10 hours of light, the guppy fry will need 12 – 14.

In fact, if they don’t get enough light, fry are particularly susceptible to dying, as they need adequate light to grow. points out that inadequate light can deform guppy fry, particularly as it relates to their spines not developing correctly.

At the same time, it’s important that guppy fry have around 6 – 8 hours of darkness, as too much light will stress them and deprive them of adequate rest.