While you might get the impression that betta fish can live in small, empty aquariums from viewing them in tiny cups in pet stores, this is far from the ideal environment. To stay healthy, betta fish need several environmental enrichments in their tanks including a day-to-night light cycle.
Light in a Betta Fish Tank
Whether it's a betta fish or any other type of fish, it's important to provide a habitat in your tank that approximates a fish's natural conditions. Maintaining proper water temperature and PH balance, a species-appropriate diet and environmental enrichment like plants and items to hide or rest on all help to make a healthy living space. Lighting is another feature that can definitely improve, or hurt, your fish's level of well-being.
Is Light Necessary for Bettas?
Providing artificial light in a betta tank isn't absolutely necessary but, "some ambient day/night cycle is good for them," says aquarium setup and maintenance expert Austin Weber of Lucky Pup Adventures. "If you think about their natural habitat, it's normally not crystal clear water like we want to see in our aquariums, although that sure makes it a lot more enjoyable for us!" He notes that, "Bettas naturally come from what are essentially rice paddies in Vietnam and the water there is muddy and dark so they can be in the dark and be fine."
Can Betta Fish See in the Dark?
Betta fish can see well enough in murky water but their vision does not work as well in pure darkness. Their vision is monocular with poor depth perception. This means they can see in opposite directions concurrently but can't adapt well to changes in light. In their natural habitat, at nighttime when the water they live in is truly dark, a betta fish will rest up and sleep so excellent night vision isn't necessary for them.
The Betta Fish Lateral Line
Instead of relying on their eyes in the dark, bettas have a "lateral line" along their bodies to help them "see" and perceive changes in their environment. This part of their anatomy helps them to sense movement and changes in the water. The line is actually a series of tiny holes along their sides.
How to Provide Light for Your Betta Fish
Austin recommends that you provide your betta fish with about eight to 10 hours of light each day but no more than that. "Too much light can be detrimental. If it's on 24/7 it's harder for them to rest and they can become stressed," Weber says. A stressed betta fish can easily become ill and can die or at the very least will live for a shorter lifespan.
Using Sunlight With Your Betta Tank
While placing a tank where there's sunlight can be an easy way to provide light, it may not be the best option for your fish. Placing a tank in direct sunlight can help improve the growth of live plants in the tank and your fish may enjoy it, but the downside is that, "you are more likely to have algae growth in the tank," according to Weber. Direct sunlight can also heat the water up past the acceptable range of temperature. If you keep your fish tank in a room that has natural light during the day but they are not in the way of direct sunlight, and the room is dark at night, this may be enough for them to be comfortable as long as the water temperature is not affected.
Using Artificial Light With Your Betta Tank
Weber says that "artificial light will give you a better view of them" compared to natural sunlight and can work well as long as you give the fish some time with the lights off. Florescent lighting can provide light for the tank and foster more live plant growth while not heating the water like incandescent lighting. They also last longer than other types of bulbs making them an economical choice. If you can't be sure you'll turn the lights off at the end of each eight to 10-hour day, you can purchase a timer to provide a regular day/night cycle.
Using Colored Artificial Light With Your Betta Tank
Many aquarium sets come with lights installed that cycle through a variety of colors. These colored lights will not affect your betta fish in any way that's different from regular "white" lights. As long as you put them on a schedule where they are on for eight to 10 hours and then off for the fish to rest, you can enjoy viewing your fish through a colorful halo of light.
Make Sure Your Betta Fish Has Light
Betta fish need light to be truly healthy, both physically and behaviorally. Just be sure that you provide them with a regular day/night cycle so they have a period of dark when they can rest. Your light source can be artificial or it can be natural as long as you avoid direct sunlight and light that might heat up the aquarium water.