Mirror In Every Tank? Myth? - Page 2

toeknee

There is a fascinating test called 'The Mirror Test' that can be used to see how self aware and animal is. Some species can tell they're looking at themselves when they see their reflection, but most can't. It's not a perfect test for many reasons, especially since many animals don't have eyes that work in a way that they can focus on a reflection, but It's still very interesting when an animal clearly passes or doesn't pass. I don't think there is anything we tend to keep in aquariums that passes the mirror test unless you have a tank large enough for a dolphin! I'm afraid it's a lot more likely a fish chooses it's mate and who to school with based on instinct honed over millenniums of evolution, not self awareness.

But google 'Mirror test' sometime, it'll bring up great videos of animials like dolphins, great apes and corvids being adorably clever and self aware. Also human babies, since the ability to recognize our own reflections is part of a child's mental development!



I don't think it causes more reflection so much as a warped reflection, like a fun-house mirror.
The salwater cleaner wrasse just recently passed the mirror test. Great read in this article.....
 

max h

The reason why I was saying a prism effect was if you look at a 90 degree prism it is intended to direct light that hits the prism walls at a 90 degree angle. One surface appears to be reflective while the other two are transparent. That way we can bend the light waves or 90 degrees. Now if we add 2 of these prisms into a device we can bend the a full 180 degrees. the military has used similar methods for hundreds of years with mirrors and prisms. The old Catseye Night vision goggles had a pair of prisms in each tube to direct the light source gathered in the objective lens down to the users eyes.

The salwater cleaner wrasse just recently passed the mirror test. Great read in this article.....

Now I have saltwater fish smarter then I am.
 

Dave125g

The reason why I was saying a prism effect was if you look at a 90 degree prism it is intended to direct light that hits the prism walls at a 90 degree angle. One surface appears to be reflective while the other two are transparent. That way we can bend the light waves or 90 degrees. Now if we add 2 of these prisms into a device we can bend the a full 180 degrees. the military has used similar methods for hundreds of years with mirrors and prisms. The old Catseye Night vision goggles had a pair of prisms in each tube to direct the light source gathered in the objective lens down to the users eyes.
Well said again. I agree with you. The prism affect is a very good way to describe it.
 

max h

Well said again. I agree with you. The prism affect is a very good way to describe it.

I did learn something in the Navy after all, other then to make people think they are drowning.
 

Pescado_Verde

The same reasoning can be use when asking how a fish knows what color it is.

Why does a black fish prefer to breed with black and mostly black fish?

How do they know this color and that they prefer it over other colors?

The only way they could seemingly know what color they are, is if they see their reflection. But then you must ask, do they know it's them?
Some dogs attack their reflection in a way seeming that they think it is another animal rather than themselves, yet somehow they still sorta know that it is them, and that they're a specific color.
Fish associate by smell. They smell themselves and associate with those that smell like them. They can't see themselves in the wild but they do know what they smell like. Each fish has its own unique smell but fish within a type will share a scent. It's not about appearances.
 

Dave125g

Fish associate by smell. They smell themselves and associate with those that smell like them. They can't see themselves in the wild but they do know what they smell like. Each fish has its own unique smell but fish within a type will share a scent. It's not about appearances.
Agree smell is important, and they don't see themselves in the wild. However appearance is important in many species for many different reasons.
A study was done on wild angel fish. What it showed is that given a choice the female will almost always chose the larger male to mate with.

Appearance is also important with territorial fish. The larger 1 usually will have the best territory.
 

Pescado_Verde

Agree smell is important, and they don't see themselves in the wild. However appearance is important in many species for many different reasons.
A study was done on wild angel fish. What it showed is that given a choice the female will almost always chose the larger male to mate with.

Appearance is also important with territorial fish. The larger 1 usually will have the best territory.
Yeah, fish are visual as well. It's hard to generalize because there are so many species and so many approaches to "solving" the demand to reproduce. And at the end of the day every other fish behavior is geared towards that one goal, reproduction. Whether it is schooling to provide safety in numbers increasing the chance of survival to reproduce or camouflage coloration to increase the odds of survival to reproduce or the development of some specialized teeth for the specific environment to eat more to survive to reproduce...lol, well, you get the idea. Some fish use smell to pick their mate, they can sense which potential mate will provide the better or more diverse genetics. Kinda like histocompatibility - why the human body can tell when tissue doesn't belong and rejects it. Fish are able to sense thru smell the "health" of other fishes and thus their suitability for mating. I can guarantee you though that they do NOT pick a mate that looks like them because it looks like them. It might look that way to us humans but there's a genetic driver - not a mirror - making that call.
 

Crazycoryfishlady

So you're saying a fish with different colors smells different?

My platies and mollies are very appearance specific and only associate with others of the same or similar colors, even if they're the same kind of fish, or from the same store/tank or same parent fish.

I've gotten fry from people from.the same parents with different colors, and yet those fry only stay and mate with those of the same color.

If they came from the same parent I can't imagine their smell is turning them off from mating.
 

AmStatic

For me it depends on lighting in the room. If the room is dark then they can see their reflection. As soon as I turn on the lights they all stop surfing the glass and flaring
 

Dave125g

For me it depends on lighting in the room. If the room is dark then they can see their reflection. As soon as I turn on the lights they all stop surfing the glass and flaring
Room lighting has to affect is in some way. I have a large enough tank that I could fit in there. Next time I pull all the fish out to do a substrate change, I'm grabbing the diving mask and going in. I wanna see this with own eyes. I wish there was a way to eliminate the mirror. It's really not good for many many fish.
 

Pescado_Verde

I'm thinking at certain angles it's the prism effect.
Like in "Caged Heat"? No, never mind, that was the prison effect.
So you're saying a fish with different colors smells different?

My platies and mollies are very appearance specific and only associate with others of the same or similar colors, even if they're the same kind of fish, or from the same store/tank or same parent fish.

I've gotten fry from people from.the same parents with different colors, and yet those fry only stay and mate with those of the same color.

If they came from the same parent I can't imagine their smell is turning them off from mating.
Observation would suggest "yes". Fish don't know what they look like. For one, they can't see themselves and 2) Even if they were to see a reflection they have no sense of self. They're not evolved enough.
Humans can stick out their arm or leg and see their own skin. Our brains are developed enough that we have a sense of self after a certain age.
If a fish is yellow that is a result of chemicals/genetics within that fish being expressed. Histocompatibility tells us that cells "recognize" like cells. I think this could certainly thru evolution be extended to sensory cells such as those used in "smelling" in fish.
It's also possible that fish are genetically designed to imprint on the shapes and colors that they are in contact with as fry. I don't know how long that would persist though. Interesting topic but probably better suited for a new thread.
 

goldface

The problem is that fish and people see differently. They don’t even see the colors like we do.
 

ValerieAdams

The problem is that fish and people see differently. They don’t even see the colors like we do.
That's what I was thinking when catching up on this. Even if we see a mirror, they may not. Or if we don't, maybe they do. I feel like our eyes are so different when looking that you can't even really compare.
 

AmStatic

Room lighting has to affect is in some way. I have a large enough tank that I could fit in there. Next time I pull all the fish out to do a substrate change, I'm grabbing the diving mask and going in. I wanna see this with own eyes. I wish there was a way to eliminate the mirror. It's really not good for many many fish.
I combatted it with a 3d background and room lighting.
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TheeLadyG

So, while I was doing a fishless cycle I was curious about this very thing so I took a video:

Thee Lady G on Instagram: “A Fish Eye View! I decided to see just exactly what the view really is from the inside of my fish tank. I wanted to know what my fish will…”

So, as you can see, the only reflection I have inside the tank is from the background where I hung a piece of black cloth against the glass. The rest of the tank is like a huge bay window into my room.

I took the cloth down to clean some water stains off of it, and just left it off. I actually like it better, because it feels like the fish are in the room with me, which they seem to like. I think that Sunny would follow me around the house like a puppy if she could.

I also read that goldfish have polarized vision, that lets them see clearly through the water surface to see predators and prey. It is likely that most fish that hunt or hang around at the surface have this same ability.
 

goldface

That's what I was thinking when catching up on this. Even if we see a mirror, they may not. Or if we don't, maybe they do. I feel like our eyes are so different when looking that you can't even really compare.
From what I’ve read years ago, fishes’ eyes are a lot less “sophisticated” than out own.
 

Dave125g

So, while I was doing a fishless cycle I was curious about this very thing so I took a video:

Thee Lady G on Instagram: “A Fish Eye View! I decided to see just exactly what the view really is from the inside of my fish tank. I wanted to know what my fish will…”

So, as you can see, the only reflection I have inside the tank is from the background where I hung a piece of black cloth against the glass. The rest of the tank is like a huge bay window into my room.

I took the cloth down to clean some water stains off of it, and just left it off. I actually like it better, because it feels like the fish are in the room with me, which they seem to like. I think that Sunny would follow me around the house like a puppy if she could.
Thank you very much. Was there any room lighting and if so how bright.
 

Crazycoryfishlady

This has more to do with my color thing, but also how they perceive light in general, and it's an interesting read.

I'm not sure how well everyone else will like this source, but it makes sense.



There was one place where it stated that it has been observed, but needs more experimentation, but some fish happen to favor a specific color, and, they can generally see us pretty clearly, which goes back to the cylinder tank, and how harmful it could be to them.

Imagine if you had to look at the world through warped goggles, on mole day we did this in chemistry by wearing mole glasses, they were warped mirrors with different colors, and we played a game where we had to hit certain shapes on a wall, this was very difficult.
Not that a fish has to hit walls, but regardless, I would find it difficult living in a world where my once normal vision was constantly warped by the outside world.
That would also affect color perception as when we look at ourselves in fun mirrors, some things blur together into other colors.

My fish react to the purple bag of food, no, not just my presence, but the actual bag.

I tested this by always coming up to my tanks anyway, and my fish don't have a strict feeding schedule.
So when I come up, they say hi, but aren't excitedly swimming back and forth or towards the surface, but when they see the bag appear, they folow it, they jump, they splash, they basically beg like a dog for a treat.
If I do this with my blue bag, they aren't quite as excited, but it's still there, and they really don't care for the orange bag.
Unsure if they relate the colors with the food, I assume it's possible, but it's possible they just like the colors too.
 

TheeLadyG

Thank you very much. Was there any room lighting and if so how bright.
My tank faces a large picture window that's across the room, and there is a row of track lights to the right. During the day it's fairly bright, much dimmer in the evening. I generally put a cloth over the tank if we're up doing things late (we're night owls and their light timer goes off at 9:30).

I want to take a better video, I think it would be fun with the fish in there!
 

Pescado_Verde

I don't know if anyone wants to migrate some of the discussion to another thread or not (have to watch out for the thread police don't ya know) but I've created a separate topic on fish and self awareness.

Are Fish Self Aware?

It's up to Dave125g .
 

Dave125g

My tank faces a large picture window that's across the room, and there is a row of track lights to the right. During the day it's fairly bright, much dimmer in the evening. I generally put a cloth over the tank if we're up doing things late (we're night owls and their light timer goes off at 9:30).

I want to take a better video, I think it would be fun with the fish in there!
So as I suspected with ambient room lighting as bright or brighter then the tank= no mirror. Can you possibly take another video with the room as dark as you can get it? For comparison.
I don't know if anyone wants to migrate some of the discussion to another thread or not (have to watch out for the thread police don't ya know) but I've created a separate topic on fish and self awareness.

Are Fish Self Aware?

It's up to Dave125g .
Yes that's correct it is a different topic. A very interesting one at that. The mods will most likely move those posts to the new thread.
 

TheeLadyG

So as I suspected with ambient room lighting as bright or brighter then the tank= no mirror. Can you possibly take another video with the room as dark as you can get it? For comparison. Yes that's correct it is a different topic. A very interesting one at that. The mods will most likely move those posts to the new thread.
You know, you can probably do the exact thing I did. All I did was put my phone in a sandwich bag and stick the camera end in the water, haha... very high tech . Then you can get an idea of your individual situation. My camera is awful in low light so I may not get a lot of info.
 

Dave125g

You know, you can probably do the exact thing I did. All I did was put my phone in a sandwich bag and stick the camera end in the water, haha... very high tech . Then you can get an idea of your individual situation. My camera is awful in low light so I may not get a lot of info.
Great idea. I'm gonna try that. Thanks.

These pictures are from the inside of the tank. The first 1 is with the room quite dark only a little light from the kitchen on. The 2nd picture is pointed at the corner of the tank with the room as dark as I could get the whole downstairs. As you can see there is a slight mirroring affect. It appears the mirror is directly related to ambient room lighting. If we want the mirror gone we will need to have the room brightly lit. Depending on the lights in the room it may cause excessive algae.
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bizaliz3

I bet its not only the level of brightness of the light in the room. I am thinking it is also affected by the angle of the light. Like, afternoon sun hitting the tank from one side for instance. Or a lamp on one end of the tank and not the other.
 

Dave125g

I bet its not only the level of brightness of the light in the room. I am thinking it is also affected by the angle of the light. Like, afternoon sun hitting the tank from one side for instance. Or a lamp on one end of the tank and not the other.
Yes. I would think, like the photo evidence shows, 1 part of the tank with no light hitting it has a very clear mirror, and with only a little bit of indirect light shows some mirror. I would think with sunlight hitting the tank there would be no mirror at all. As shown by the video posted above.

What we need to ask ourselves is, are our fish stressed out by the mirror, of course it's different for each species. If so we should work to remove it. If there not then there's no need to correct it. The other thing is are we gonna get excesive algae? If we use sunlight then probably. If we just use soft white bulbs we should be fine. Are these corrections worth it? We have to take electricity cost and other factors into account.

In short it's more complex then I realized. Lol
 

Ulu

I have to mention that, like people, all fish do not have equal eyesight. Some fish will see farther and better than other fish of the same species.

While we are waiting for Dave's trick with the sandwich bag, I'm going to comment that I do have a 16 bow front. Here's a photo I took a couple months back.

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I have also had fish in jugs and bottles. It does not appear to be a problem for the fish. In fact little Betta Boy loves to swim up inside this bottle and sleep above his tank.
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There is a classic problem in physics 101 about a fish and a fisherman and it regards the index of refraction of various transparent materials. "How close can a 6ft tall fisherman get to the edge of the water before a fish two feet down and three feet away from the edge can see him?"

Now this is a very complicated problem, but in physics 101 they reduce it down to some simple trigonometric equations and the differing Factor of refractive indices, of pure air and pure water.

Air, water, glass Etc all bend light different amounts. Add some dust or silt or something and it changes even more.

Photons react differently when they pass through different materials. Because photons come in all different colors, or wavelengths as we say, each color reacts differently for two different materials. This is why prisms can bend light and expose its many colors.

The air, the glas, the water, the fish's eye's lens, and the rest of its eye are all factors in the equation of how far any particular color of light bends.

Now here's the really interesting thing that if you read all the way down to here you get to find out.

That problem about can the fish see the fisherman changes rapidly when things start to move.

If you see something moving in a linear fashion it appears to move uniformly.

But light moving through materials are glass and water and fish eye which are all moving relative to each other, can sweep dramatically in a non-linear fashion.

This is how you can take a search light and make it pretend to be a UFO suddenly streaking across the heavens from rest. It appears to accelerate at incredible speeds, but all you did was wiggle a light on the ground.

Now imagine that you run that light through refractive materials that move. You can achieve that same impossibly rapid sweeping effect without moving the light.

With this all in mind things can appear suddenly to fish and disappear just as suddenly, including Reflections from oblique surfaces.

When you look square on to all the materials involved, the index of refraction of them has approximately no effect. As soon as you get off axis a little bit, things can appear to bend, distort , or dart rapidly.
 

bizaliz3

Yes. I would think, like the photo evidence shows, 1 part of the tank with no light hitting it has a very clear mirror, and with only a little bit of indirect light shows some mirror. I would thing with sunlight hitting the tank there would be no mirror at all. As shown by the video posted above.

What we need to ask ourselves is, are our fish stressed out by the mirror, of course it's different for each species. If so we should work to remove it. If there not then there's no need to correct it. The other thing is are we gonna get excesive algae? If we use sunlight then probably. If we just use soft white bulbs we should be fine. Are these corrections worth it? We have to take electricity cost and other factors into account.

In short it's more complex then I relied. Lol

I am going to guess they ARE stressed by it. I think my angels are very stressed when they think there are other angels right next to their eggs. And bettas are quite possibly flaring at a reflection of some kind. And I wouldn't be surprised if glass surfing also has something to do with the seeing themselves going up and down the sides all fast and stuff. Or only seeing themselves at certain angels, so they are surfing the glass like crazy trying to see what they thought they saw when they were at a different angle. haha
 

toeknee

I wonder how the presence of a mirroring effect or lack of effects fish behavior in general. When it gets dark and I have lights off around my tank with tank lights still on all my fish always seem more active and bold. As if they have a higher sense of security.
 

Ulu

I don't think reflections affect them as much as motion.

Their eyes make things look distorted so they have better sight of things coming at them obliquely.

Things coming at a fish appear to "dart" into view, because they have (to differing extents) "fisheye" vision.
 

Dave125g

I am going to guess they ARE stressed by it. I think my angels are very stressed when they think there are other angels right next to their eggs. And bettas are quite possibly flaring at a reflection of some kind. And I wouldn't be surprised if glass surfing also has something to do with the seeing themselves going up and down the sides all fast and stuff. Or only seeing themselves at certain angels, so they are surfing the glass like crazy trying to see what they thought they saw when they were at a different angle. haha
I think some fish are definitely frightened by there reflection. As the link a few pages back says. I also think some (schooling) fish may even be comforted by it. I also think that since most tanks are so bright there's no need for room lights to be on. Therefore most tanks have a well defined mirror in them.
I wonder how the presence of a mirroring effect or lack of effects fish behavior in general. When it gets dark and I have lights off around my tank with tank lights still on all my fish always seem more active and bold. As if they have a higher sense of security.
With the tank lights off there's almost no mirror, as the room is almost always brighter then the tank. When fish are calm and not moving much it indicates no stress, more often then not. By contrast when fish are flying around the tank that could indicate stress.

Here's another question. Aquarium raised fish.... Do they get use to the mirror? As opposed to wild caught fish who have never seen it.
 

Shellback

I'll go dig up my GoPro camera and and see what it does in one of the tanks. It may take a little while,

Max, why did you have your GoPro buried? What's down there to take pics of?
 

Dave125g

Max, why did you have your GoPro buried? What's down there to take pics of?
Good 1. Elvis mabee?
 

max h

Max, why did you have your GoPro buried? What's down there to take pics of?

The GoPro gets used for everything from the dogs, shooting, boating, and the car. From time to time especially lately since I moved things get a little displaced.
 

H2O Concierge

When we look in the front of our tank at the side walls, we see a mirror. Is that what the fish see? I have seen pictures taken from inside the tank, with no mirroring affect. Can someone test this with a water proof camera? Do Bettas flare at there reflection? do corrys school with there own reflection? These are all reasons given to people who ask. I think fish can see out as well as we can see in. Mabee there is a mirror depending on room lighting? Can we test this?
In the attached photo there is only 1 fish. I can see her reflection, but can she?
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Do you have a set of goggles?

It would be awesome if we were somehow able to design a tank where the fish can’t see their reflections. The fish would be a lot less stressed and they might venture away from the glass more often.
I am sure that it depends on what is external to the tank and the amount of light, and it's relationship to the interior light. Of course a 3D covering (such as a rockscape) on 3 sides would do it, but then you only have front to back viewing. Perhaps you would only need to remove the interior right angles with something not reflective. It inevitably did lead us to the question of reflections in a Bow.
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But what about the even more perplexing
...a Hex tank
 

Dave125g

Do you have a set of goggles?
I do. But I'm not climbing in Lol I'll get 1 of the kids to do it.

I am sure that it depends on what is external to the tank and the amount of light, and it's relationship to the interior light. Of course a 3D covering (such as a rockscape) on 3 sides would do it, but then you only have front to back viewing. Perhaps you would only need to remove the interior right angles with something not reflective. It inevitably did lead us to the question of reflections in a Bow.
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But what about the even more perplexing
...a Hex tank
This thread raised lots of questions.
Are some fish comforted by there reflection?

Are some frightened by it?

Should we try to correct it?

How does backgrounds effect it?

Different shaped tanks?

Are we all nuts?
Lol
 

BusterBot28

I am sure that it depends on what is external to the tank and the amount of light, and it's relationship to the interior light. Of course a 3D covering (such as a rockscape) on 3 sides would do it, but then you only have front to back viewing. Perhaps you would only need to remove the interior right angles with something not reflective. It inevitably did lead us to the question of reflections in a Bow.
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But what about the even more perplexing
...a Hex tank

I just got a 33g hex tank so when it is set up and running I will see if I can borrow a GoPro and do some tests!
 

Dave125g

I just got a 33g hex tank so when it is set up and running I will see if I can borrow a GoPro and do some tests!
Awesome. Please post those pictures.
 

BigManAquatics

This thread raised lots of questions.
Are some fish comforted by there reflection?

Are some frightened by it?

Should we try to correct it?

How does backgrounds effect it?

Different shaped tanks?

Are we all nuts?
Lol
Yes we are ALL nuts!! As to the other questions...remains to be seen.
 

Dave125g

Thought I'd revive this thread, and sumerize it a bit. When we look at our tank we see a mirror on the sides, but what do the fish see?
When we look in the front of our tank at the side walls, we see a mirror. Is that what the fish see? I have seen pictures taken from inside the tank, with no mirroring affect. Can someone test this with a water proof camera? Do Bettas flare at there reflection? do corrys school with there own reflection? These are all reasons given to people who ask. I think fish can see out as well as we can see in. Mabee there is a mirror depending on room lighting? Can we test this?
In the attached photo there is only 1 fish. I can see her reflection, but can she?
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Here's some pictures from inside the tank sorry about the quality some it's hard to shoot completely free hand. But the shot angled from the front glass to the side glass shows a mirror on the front glass. Shooting directly through the side glass no mirror. Now one of the other shots is down the length of the tank towards the heavily planted end, you can see the 100 gallon through the front glass without a mirror effect.
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So, while I was doing a fishless cycle I was curious about this very thing so I took a video:

Thee Lady G on Instagram: “A Fish Eye View! I decided to see just exactly what the view really is from the inside of my fish tank. I wanted to know what my fish will…”

So, as you can see, the only reflection I have inside the tank is from the background where I hung a piece of black cloth against the glass. The rest of the tank is like a huge bay window into my room.

I took the cloth down to clean some water stains off of it, and just left it off. I actually like it better, because it feels like the fish are in the room with me, which they seem to like. I think that Sunny would follow me around the house like a puppy if she could.
These pictures are from the inside of the tank. The first 1 is with the room quite dark only a little light from the kitchen on. The 2nd picture is pointed at the corner of the tank with the room as dark as I could get the whole downstairs. As you can see there is a slight mirroring affect. It appears the mirror is directly related to ambient room lighting. If we want the mirror gone we will need to have the room brightly lit. Depending on the lights in the room it may cause excessive algae.
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The above photos, with the exception of the first, were all taken from inside of the tank. As you can see depending on room lighting there is a mirror. More room light =less mirror. Less room light = more mirror.
 

BigManAquatics

I do know for sure my bettas see themselves at least sometimes, as they have flared and crashed into their reflections. I do think they have got used to it, don't see such behavior very often anymore
 

Shade89

I saw you mention this topic in one of my threads and it reminded me that I took a picture like this 5 years ago at an aquarium. It always freaked me out a bit xD
 

H2O Concierge

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I saw you mention this topic in one of my threads and it reminded me that I took a picture like this 5 years ago at an aquarium. It always freaked me out a bit xD
I saw you mention this topic in one of my threads and it reminded me that I took a picture like this 5 years ago at an aquarium. It always freaked me out a bit xD
Here are a couple of my own. Are there 3 or 4 loaches? Check out the weird reflection of the table next to the tank on a piece of black slate. The pic was taken looking down from the short side of the 75g.
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View media item 241245
 

TheeLadyG

Do keep in mind though, what you see through the front of the tank is *not* what the fish see from the inside of the tank. The only way to really know is to dunk a camera in your tank!
 

BettaMaxx

Do keep in mind though, what you see through the front of the tank is *not* what the fish see from the inside of the tank. The only way to really know is to dunk a camera in your tank!
I'm actually surprised we don't have more photos on here from INSIDE the tank in the water. If I had a GoPro I would do this and post immediately.
 

TheeLadyG

I'm actually surprised we don't have more photos on here from INSIDE the tank in the water. If I had a GoPro I would do this and post immediately.
right?? I took video while I was fishless cycling my tank by putting my phone in a ziploc bag, because I was curious what the fish see. I was so surprised about the lack of 'mirror.' I want a waterproof camera to put in my tank and leave there. I wish I could shrink down and just get IN my tank, how fun would that be??
 

Dave125g

The first 2 pages of this thread have a couple of pictures from inside the tank. Not sure why people keep posting pics from the outside.

My tank is actualy large enough for me to climb in and look out, but I fear it would really spook my fish too much.
 

Kathryn Crook

I doubt most ppl have seen this stand up comic...but his name is John Capparulo and he has a bit about fishtanks where he decided against one as a pet cuz he acted out a goldfish seeing its reflection, being shocked, swimming round, and being shocked by its reflection again. Lol. Sorry...just keeps entering my mind as funny every time I see this thread...lol
 

Skavatar

some science on reflection, and light angle

"https://en.wikipedia.org/wiki/Tot... . If light is going from a dense medium like water to a less dense one like air, the angle of incidence increases according to Snell's law. If the angle of incidence is more than 48.471 degrees (arcsin⁡(1/n)" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">arcsin(1/n)arcsin⁡(1/n) where n=1.3358" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">n=1.3358n=1.3358 is the refractive index) on the water side, it would need to be more than 90 degrees on the air side to satisfy the law. In that case it can't get out at all.

Moreover there's a smooth lead-up to total internal reflection. There's always some light that's internally reflected, and the fraction just gradually increases to 100% at the critical angle. So the walls still look fairly mirror-like for angles of somewhat less than 48.4 degrees."

and

"Critical angle – The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at an interface between the denser and less dense medium, at which the light is refracted along the interface. When the critical angle is exceeded, the light is totally reflected back into the denser medium. The critical angle varies with the indices of refraction of the two media with the relationship: Sin Ic = n n' Where Ic is the critical angle; n’ the refractive index of the less dense medium, and n the refractive index of the denser medium."
https://www2.optics.rochester.edu/workgroups/berger/EDay/Optics demonstrations for the classroom.pdf
 

Dave125g

some science on reflection, and light angle

" PhD in Physics, The University of Queensland, physicist with National Astronomical Observatory of Japan
· Author has 8.6k answers and 9.5m answer views


It's a case of "total internal reflection": https://en.wikipedia.org/wiki/Tot... . If light is going from a dense medium like water to a less dense one like air, the angle of incidence increases according to Snell's law. If the angle of incidence is more than 48.471 degrees n=1.3358n=1.3358 is the refractive index) on the water side, it would need to be more than 90 degrees on the air side to satisfy the law. In that case it can't get out at all.

Moreover there's a smooth lead-up to total internal reflection. There's always some light that's internally reflected, and the fraction just gradually increases to 100% at the critical angle. So the walls still look fairly mirror-like for angles of somewhat less than 48.4 degrees."

and

"Critical angle – The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at an interface between the denser and less dense medium, at which the light is refracted along the interface. When the critical angle is exceeded, the light is totally reflected back into the denser medium. The critical angle varies with the indices of refraction of the two media with the relationship: Sin Ic = n n' Where Ic is the critical angle; n’ the refractive index of the less dense medium, and n the refractive index of the denser medium."
https://www2.optics.rochester.edu/workgroups/berger/EDay/Optics demonstrations for the classroom.pdf
Thank you very much for the detailed analysis and the links. It's much appreciated.
 

Kathryn Crook

some science on reflection, and light angle

PhD in Physics, The University of Queensland, physicist with National Astronomical Observatory of Japan
· Author has 8.6k answers and 9.5m answer views


It's a case of "total internal reflection": https://en.wikipedia.org/wiki/Tot... . If light is going from a dense medium like water to a less dense one like air, the angle of incidence increases according to Snell's law. If the angle of incidence is more than 48.471 degrees (arcsin⁡(1/n)" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">arcsin(1/n)arcsin⁡(1/n) where n=1.3358" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">n=1.3358n=1.3358 is the refractive index) on the water side, it would need to be more than 90 degrees on the air side to satisfy the law. In that case it can't get out at all.

Moreover there's a smooth lead-up to total internal reflection. There's always some light that's internally reflected, and the fraction just gradually increases to 100% at the critical angle. So the walls still look fairly mirror-like for angles of somewhat less than 48.4 degrees."

and

"Critical angle – The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at an interface between the denser and less dense medium, at which the light is refracted along the interface. When the critical angle is exceeded, the light is totally reflected back into the denser medium. The critical angle varies with the indices of refraction of the two media with the relationship: Sin Ic = n n' Where Ic is the critical angle; n’ the refractive index of the less dense medium, and n the refractive index of the denser medium."
https://www2.optics.rochester.edu/workgroups/berger/EDay/Optics demonstrations for the classroom.pdf
“Blinded me with science!” Nm...you millennial types won't get it...lol
 

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