Do Arowana Need Light At Night? {Which Light Is The Best?}

Are you thinking about keeping the light on at night for your Arowana? Will the lights at night reduce or add more stress? In this article, we’ll discuss the topic of keeping the lights on at night for Arowana.

Do Arowana Need Light At Night? No. Arowana are diurnal. They are active in the day and asleep at night. Turn off the lights to allow rest and better overall health.

Why Do Arowana Need Light At Night?

There are some arowana keepers who feel that keeping the lights on night works for them. It’s important to follow a schedule that works for you and your marine life.

The belief is that arowana will remain more calm, start less fights and be less jumpy with the lights on. They may get startled more at night with the lights off and they may not eat because of it.

We simply cannot advocate or agree with this position. We encourage you to keep a circadian rhythm for diurnal fish like arowana.

Will Night Lights Make My Arowana Shine?

Your arowana would look great under any light. You can try black lights or colored LED lights to give your arowana the extra pop in their vibrancy.

These surface swimmers prefer a lengthy period of darkness at night to rest and recover for a new day. You can keep the black lights on starting from the evening until it’s time for everyone to sleep. At this point, it’s light out for the house.

Some lights allow you to dim it without completely shutting it off. Your arowana may look majestic under such conditions. The shine on their scales depends more on their diet and water quality.

When Should I Turn Off The Lights For Arowana?

Since arowana are most active during the day, the best time to turn off the lights at night. They will receive plenty of indirect light when you are out of the house during the day as well.

Turn off the lights when you decide to sleep at night. Keep them off until the following evening if you wish.

You can also switch the lights to a red or LED colored tan light in the late evening. When it’s time for bed, turn off all the lights.

Do Lights Shock or Startle Arowana?

Remember that arowana swim in murky rivers and streams. The visibility is lower and the lighting is dim. The conditions in a community tank are usually brighter than arowana are adapted to. If you’re keeping only arowana, you may decide to use darker or dimmer lights.

When it’s time to turn on the lights in the tank, try to do so gradually if possible. A sudden flick of the switch may stress, shock or startle your arowana.

If you can open the curtains instead and allow natural light in first before switching on tank lights, your arowana may feel more relaxed.

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What Happens When I Keep My Arowana Tank Lights On At Night?

If you choose to leave the lights on all night, the following possibilities may occur:

  • rapid algae growth
  • stressed arowana
  • lack of appetite
  • constant hiding
  • jumpy
  • more fights


Have you ever accidentally left your tank lights on over the weekend while you were away? Did you notice string algae, gunk or a dirtier tank when you returned? Blame the light.

Light provides the nutrients for the fastest growing plant matter in the tank to thrive. Unfortunately, the algae wins ahead of all others.


Arowana who don’t receive the darkness they crave for at least 5-12 hours are bound to be stressed. Their natural conditions are being altered in a such a way that full rest cannot be achieved. Stress leads to illness or lowered lifespans.

Lack of Appetite

Some arowana like to eat at
night. Others are picky eaters, especially when we are training them to eat mostly pellets instead of live foods.

Your arowana might eat as soon the lights turn back on for their breakfast time. A long period of darkness may cue their hunger response when the lights turn on.

Constant Hiding

An irritable arowana that hasn’t gotten enough rest may try to find a spot furthest away from the light to hide. If there are decorations or rooted plants, your arowana may retreat to find a darker spot if possible.


These fish can jump! They developed this skill to feast on insects above the surface of the water. The instinct to jumping may kick in when they feel the need to get out of the tank. Poor water quality, aggressive tankmates or bright lights may lead to this undesired reaction.

More Fights

Some say that arowana like to fight in the dark. This is why they keep the lights on at night. An irritated arowana without a full night’s rest may wish to fight during the day as well.

How Many Hours Should I  Leave My Tank Light On Per Day?

Start slowly to make sure you don’t get a sudden and wanted level of algae growth. 8-10 hours per day is recommended for new aquariums. Watch and wait 2-3 weeks.

If there is no extra algae growth, then you can increase the duration of aquarium lighting. The limit should be around 12-14 hours. Fish do enjoy 12 hours of lights off every night. The choice is yours to make.

What Do Arowana Get From Aquarium light?

Arowana can easily survive and enjoy their lives in your tank without any tank lights. We enjoy the lighting more than they do. The scales on arowana shine and we prefer to see their vibrancy.

The lights also help us observe any issues with the tank’s overall ecosystem. When we’re done with maintenance and enjoyment, we should turn off the lights for our arowana to resume their natural cycle under dimmer conditions.

Should I Get A Timer For My Arowana?

Turning off the lights is crucial for the health of our arowana and the tank as a whole. We want to limit growth of algae while also making sure these elegant fish enjoy the rest they need.

A timer helps set a schedule and prevents us from forgetting. Leaving the lights on for extended periods may stress out your arowana.

The timer is cheap and easy to set up. It’s best to let it work on its own under a 12 hour schedule or even shorter periods of light because arowana are fine with dim and dark waters.


Thanks for visiting and we hope to see you again for another article on Arowana or any other marine life that interests you. 

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.