# Blue Light at Night, thoughts?



## blubird101 (Jan 25, 2019)

Hello! So I have a tank at home now that has a light that came with 3 settings, regular white, blue, and off. I've always heard the blue light is meant for nighttime. 

Well, I've tried turning on the blue light at night and it seems like my Betta is still as active as he is during the day, and does flare sometimes too. When I turn off the light though, he does go to bed after a little bit and isn't as active.
Believe me, I would love to keep the blue light on at night as I can still see the betta and its relaxing to watch at night.  But, I also keep reptiles and I know that even though you can put a blue or red light in, they can still see the fact that its "bright" even if its a different color, so its basically the same as leaving a light on at all times. I feel its important for my fish to have a good light and dark cycle but what are your thoughts?

Do fish benefit from a blue light at night? What are your thoughts? Do any of you use a blue light at night?


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## RussellTheShihTzu (Mar 19, 2013)

I use blue lights at night in my Betta tanks that also house shy or nighttime fish like my Hara jerdoni and some Plecos. Never noticed the other fish "staying awake;: but I also turn off the room lights.

I do, though, turn all of the tank lights off when acclimating new fish.


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## blubird101 (Jan 25, 2019)

Hmm...maybe the lights I have in mine are just too strong. I have noticed that my cory does come out more at night with the blue light on, so I think he likes it.

I tried again last night and I noticed that my betta kept flaring at all the sides of glass. He doesn't usually flare at the glass during the day so the blue light must be hitting the reflection weird or something.


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## Old Dog 59 (Nov 11, 2018)

I use my blue light in the early morning to make the light change easier on Ben's eyes. He seems to wake up easier, and not have an attitude before breakfast.


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## blubird101 (Jan 25, 2019)

Yeah, I've been doing that lately as well and Caspian seems to like that. I scared the crap out of him the other day when I went straight from dark to light, the poor dear! haha


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## Old Dog 59 (Nov 11, 2018)

I did that once to Ben and he ran head on into the front of the tank. He backed off and gave a look as like (What who put that there.)


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## RussellTheShihTzu (Mar 19, 2013)

blubird101 said:


> Hmm...maybe the lights I have in mine are just too strong. I have noticed that my cory does come out more at night with the blue light on, so I think he likes it.
> 
> I tried again last night and I noticed that my betta kept flaring at all the sides of glass. He doesn't usually flare at the glass during the day so the blue light must be hitting the reflection weird or something.


As with many things, food, decor, etc., it can take time for fish to get used to something different.


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## blubird101 (Jan 25, 2019)

Is there any benefit to it though? Or is it all just for our viewing? Fish can still see the blue light, right?


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## OrchidxBetta (Mar 18, 2016)

blubird101 said:


> Well, I've tried turning on the blue light at night and it seems like my Betta is still as active as he is during the day, and does flare sometimes too. When I turn off the light though, he does go to bed after a little bit and isn't as active.


Same. Even on the dimmest blue light, my Betta is still active. I just turn off all lights so the living room is dark.


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## Thunderstar (Mar 21, 2019)

I have a tank with 3 different colour light settings that can also be dimmed. It has purple (blue&red leds), white and a combination of the blue,red and white leds. During the day I have it on the combi light at full, but I turn it to purple an hour or so before i go to bed and then dim it just before I put my bedroom light off ( Storm lives in my bedroom). Storm and his tank mates seem to slow down once it’s changed and then settle once I dim it.


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## bettatanksalot (Mar 6, 2018)

I have a blue moonlight on my dwarf puffer tank, I don’t use it because it still can cause algae growth and as others have said my fish seems more active when it’s on.


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## RussellTheShihTzu (Mar 19, 2013)

There is a wide misconception that the purpose of blue/purple lights is to send fish to "sleep." They are mainly used by aquarists to observe shy fish and those most active at night. As noted in Post #4, they also ease the transition to white light. I have noticed that, in Betta, level of activity depends on the individual fish and whether the room lights are left on.

As to algae, I've also read blue lights can contribute but I've only seen that stated about overhead blue lights. I use a blue light bubble wand (not as strong) and haven't noticed algae growth. Wonder if that's the difference? Or is it the lights point up instead of down? :dunno:

Thought everyone might find the following of interest.

From the National Ocean Service of the National Oceanic and Atmospheric Administration. U.S. Department of Commerce (June 25, 2018):

The nature of fish "sleep" is an area of active research. While fish do not sleep in the same way that land mammals sleep, most fish do rest.

Research shows that fish may reduce their activity and metabolism while remaining alert to danger. Some fish float in place, some wedge themselves into a secure spot in the mud or coral, and some even locate a suitable nest. These periods of "suspended animation" may perform the same restorative functions as sleep does in people.


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## grre (Jun 11, 2019)

I’ve been doing a lot of research lately on fish sleep (working on a philosophy book about fish consciousness more generally) the problem is, sleep is debated even in humans for its “true” purpose and then, when in fact it does “occur” is complicated. 

Fish dont have a neocortex/paleocortex (the latter for birds) which scientists have argued is necessary to reach REM sleep ie. the sleep where we mammals + birds dream, but excluding convergent evolution (different functions can evolve in different ways) even if fish dont REM sleep-behaviourally speaking they DO sleep and need 9 hours or so rest time (sleep being characterized as slower breathing/motion patterns/responsiveness/lethargy. Which is why its important to maintain a healthy sleep/day cycle (I used to get SOO angry at my housemates when theyd leave a lamp on in the living room, could they not see that my fish would be obviously affected?!?! Would they want to sleep with a bright horrible light directly in their faces?!? probably not). I also read somewhere once upon a time that Bettas eyes, while actually very good-do have trouble reacting instantly to sudden light changes (not unlike ours) which is why they appear so startled. I have my baby fish on my bedside table so when I come home late and am in my room I always try to be respectful that she is probably sleeping and wouldnt appreciate me turning on all the lights...I also would get very angry when people would barge into my room back when I lived in a house with multiple people, and they would just flick on my overhead light to search for something in my room ect. thus waking up all my fish...tf!!! (if i lived there longer probably would have ended up taking the battery out of the dang thing). As someone with an autism spectrum disorder artificial lighting has always been something I’m cautious about so for me, it was always common sense to try to allow my fish the most natural day/night cycle as possible, as I only use artificial lights at night when I’m reading ...

I appreciate blue light as a way to transition to night or day light in situations where natural light isnt possible but at the same time, I’m irritated with the waay pet stores Ive seen have been marketing blue light as a new way to experience ones fish “even in the dark”! It seems cruel and unfair-these fish are not here for our purely ornamental enjoyment, and need proper sleep cycles too.


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## RussellTheShihTzu (Mar 19, 2013)

Perhaps we should differentiate between overhead light from a hood...which lights an entire tank...and a single strand of moonlight/blue lights against a back wall? I have always used the latter so if my experience is not the same as with the former it was my mistake to lump the two types of blue light together and I apologize.

Any scientific study I've found shows fish do not sleep as the average person defines it. Fish, as noted in Post #12, go into a sort of "suspended animation." To call it "sleep" is misleading at best. Using the word "sleep" in any context referring to fish makes for confusion; especially when so many are prone to anthropomorphize.

From my own experience, using the moonlight/blue light in a bubble wand does not disturb the rest of diurnal fish. They do, indeed, seem to be in suspended animation. They become still and float in one place exactly as they do without the moonlight. At the same time, nocturnal and shy fish will be out and feed as not seen under white light. It is more than interesting to view the nighttime behavior of a shoal of 20 Neon Tetra resting as one and perfectly still.

We can all agree it is very important for all animals, fish included, to have a period of rest. If you observe your fish reacting adversely to blue lights you should not use them. If your experience is as mine, then use them. 

It is only you who can judge what does or does not work for your fish.


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