Are Betta Fish Afraid Of The Dark? – Should The Lights Be On?

Do Betta Fish Like Mirrors

Do you keep the aquarium light ON all the time? well, we know some Betta-keepers who do that. their reasoning is Bettas are afraid of the dark. They tend to stop moving around much as soon as the light goes out. If so, it’s concerning. But is it really true?

Bettas are not afraid of the dark at all. In fact, they are diurnal. They don’t hate or love darkness. All they need is a circadian rhythm to tell the difference between day and night.

So, they need both brightness and darkness. But sometimes it might not be possible for you as a Betta-keeper. What will happen to your Betta if it needs to live in darkness for an extended period? Well, let’s find out.

Key Takeaways

  • Bettas need darkness as much as brightness.
  • The dark period shouldn’t exceed more than 12 hours.
  • Bettas have slow iris restricting their eyesight in the dark.
  • Bettas can’t eat anything in the darkness.
  • An exchange between darkness and light is necessary to activate the circadian rhythm.

Do Betta Fish Hate Darkness? Or Afraid Of It?

Betta fish is not a cave dweller. Unlike many other timid aquarium fish, Bettas are highly adventurous and active. You will find them moving on top of the tank during day time and enjoy the strong current for a while. Another reason why they go upside is to have better access to natural light. Yes, Bettas love brightness, but there’s an extent to it.

If the room has access to natural light, make sure you turn on the ceiling light for at least 4 to 5 hours. The sunlight coming through the window will provide enough brightness for the fish to function. Also, it imitates the vague and warm light setting usually seen in Betta’s wild habitats. Their vision is blurry at this point. But they can figure out the shape of food or plants without much trouble.

 However, not every room is built with an attached window. In that case, make sure a dimmed light is always turned on. Only activate the aquarium light (which is more harsh) for 4-5 hours per day.

cornflower blue betta

Will My Betta Fish Die In Darkness?

Nope. Your Betta won’t die in darkness. We understand that it’s not possible to carry around your aquarium everywhere you go. Sometimes when you are leaving the house for a few days, you wonder whether to keep the aquarium light ON or off.

See also  Can A Light Be Too Bright For A Betta Fish?

Since keeping the lights ON would increase the stress level and affect Betta’s sleeping cycle, some experts suggest keeping the lights off. But is it harmful in any way? Well, it kind of is. Even though you don’t have to worry about seeing your fish dead once you get back home, there are still consequences. Take a look.

1. Difficult To See Or Eat

Bettas don’t see anything in the dark. Once you turn off that aquarium light, Bettas assume it’s night-time and try to sleep. So, leaving them with plenty of food in the dark won’t do them any favor. Because how are they supposed to eat if they can’t even locate the pieces? That’s alarming.

Siamese fighting fish or bettas have monocular vision. On the good side, they can see a wide range of areas at once. In the wild, it helps them be aware of any predators near them. However, with such a gift comes a bad side: not being able to see a thing when the light goes off.

2. They Get Weaker

We don’t have to say much about this side effect. If you keep the lights off for a few days, you won’t come back to the healthy and lively fish you left behind. Lighting is considered more crucial than regular meals when it comes to bettas. Crazy, isn’t it? According to experts, bettas can survive without food for a few days (like fasting).

However, bettas tend to become anxious and stressed when the lights are out for so long. It slowly tires them out, leading to a weaker and more sensitive Betta.

3. Lose Their Rhythm

Bettas don’t have eyelids. So, there’s no way they can be sound asleep regardless of how bright or dark an area is. Their open eyes quickly catch any change in lighting arrangement. That’s why you can manipulate your Betta’s daily schedule using aquarium lights. When the lights are on, the bettas know it’s time to eat food.

When the lights are out, they are automatically prepared to end the day. It’s called circadian rhythm. Such rhythm helps a Betta stay healthy and happy. However, when there is continuous darkness for a long time, this rhythm gets broken. Forcing the betta towards an uncertain lifestyle.

blue white gorgeous betta fish
Owner: Sean Aurellio

How Long Can A Betta Fish Tolerate Darkness?

Betta fish don’t enjoy being in darkness for long hours. They only need it during nap times. The tank should have sufficient lighting once they are awake. If we have to calculate this number, a betta fish usually sleeps for 8 to 10 hours per day. So, the tank should be dark only for that long.

See also  Betta Fish Lighting Cycle: How Long Do Betta Fish Need Light?

However, as we discussed earlier, you might have no option but to leave the house in darkness for a couple of days. Here’s a table that shows how long is too long.

Hours Spend In DarknessBetta BehaviorRemark
8-12 hoursUsually, sleep or restCompletely healthy
24 hoursGets a bit stressed, don’t eat anything.It’s alright.
3 or 4 daysExtremely stressed. Fast for the whole time. Gets weaker.Alarming; needs to be taken care of immediately.
Beyond 4 daysBecomes lethargic and hides away. Loses appetite and feels super tired and anxious.Highly dangerous. Betta will start showing signs of illness.

It’s understandable when you are moving to another house; you have to pack the aquarium too. As you can see, leaving the betta in darkness for one or two days would be alright (not that damaging). But it shouldn’t be over that. once you leave the betta like that for 3 or 4 days in a row, the anxiety and stress give birth to many medical illnesses.

 Also, please remember when you are traveling, don’t put any food inside the tank. The pellets or live food will start to rot if not eaten within a certain time frame. But that’s not possible since bettas can’t even see the food ahead of them.

Note: If it’s been over one day in complete darkness, please don’t turn on the lights suddenly. It can startle the fish, causing even more stress. It would be better to open the window and let the natural light in your room. Let the fish adjust for 15 to 20 minutes. Then, turn on the aquarium LED lights.

Is Darkness Good For Bettas In Anyway?

Darkness is not fully bad or good for bettas. All Bettas ask for is a routine between darkness and light. We have said too much about how bad darkness can be for a betta. However, some bettas prefer a dimmed light setting over brightness. Let’s see the various ways darkness can benefit a Betta.

1. For Sleeping Better

Darkness is a must for sleeping better. Betta keepers are advised to dim the room, including the aquarium light, at night. That’s how the Bettas know the difference in the time frame.

It is reported that Bettas become very restless and find it difficult to doze off for a long time in the presence of light. Darkness imitates the shift from day to night. Bettas quickly pick up the cues and rush to take some rest. You will see your Betta sleeping longer and better in the dark.

See also  Are Crowntail Bettas More Aggressive?

2. Reducing Stress

Exposing your Betta to harsh LED light or sunlight is a big NO. It increases their anxiety. They can’t take a nap even if they want to. Especially if you have just brought a Betta in your time, it needs time adjusting. And interestingly, it does so very well in deemed lighting. The overexposure to light causes the fish to notice drastic changes in its surroundings. It only increases stress and causes various other problems.

3. Managing Digestion

Bettas don’t know when to stop eating. You will see the Betta’s mouth moving as long as there is food. It continues chewing everything in its sight. It’s always on the look for more food regardless of how full it already is. That’s why darkness is necessary to put a pause on this behavior.

Once the lights are out, Betta can’t see a thing and hopefully can’t eat a thing. The fasting period helps to digest the food it consumed earlier. Not to mention, effective digestion is the key to avoiding issues like constipation.

Can Bettas Eat In The Dark?

Bettas can’t eat in the dark. They need at least some vague lighting to locate their food. That’s because Bettas have weaker eyesight. Their iris is not wide enough, and they don’t see well if the light is dimmed.

In nature, Bettas tend to stay on top of a pond and hunt only during the day. Can you guess why? Yes, because that’s when they can actually see. Once the sun sets and there’s no alternative source of lighting, Bettas prefer resting or hiding. So, if you have been offering food to your betta in the dark, you know why it couldn’t eat properly.

Not just this, but providing food in darkness can also mess with your Betta’s eating and sleeping habit. Betta’s natural instinct is to sleep at night and eat when there’s light. By offering food in the dark, you are forcing the fish to change its daily routine.

Now, it has to stay awake and look for food (but can’t find it due to the darkness) at night. It will make the Betta cranky, stressed, and somewhat ill. Please avoid dropping food into the aquarium when there’s no light.

Before You Leave!!

Bettas are not afraid of darkness. But it’s just better to lower the light to let the fish function. Don’t forget both uninterrupted brightness and darkness has the same negative effects on a betta’s development. To understand the topic better, we suggest you check out our take on Betta’s lighting cycle. It’s going to be fun, we promise.

Betta Fish Lighting Cycle: How Long Do Betta Fish Need Light?

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Muntaseer Rahman

About Author

Hello, I’m Muntaseer Rahman, the owner of I’m passionate about aquarium pets like shrimps, snails, crabs, and crayfish. I’ve created this website to share my expertise and help you provide better care for these amazing pets.


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