Advice on one-way films for studying fish

[Fish1]

Hello everyone,

This is an unusual request so please feel free to let me know if I should post elsewhere.

We are looking for a one-way view solution for a study on fish behavior. We are looking at how fish choose who to group with. We will have a fish in one tank that can see two groups of fish in neighboring tanks.

We want to use a one-way coating/film on a piece of glass or PVC so that the subject fish can see the groups, but the group can’t see the subject fish. (So, the group of fish is like the suspect in an interrogation room – we’ll make their tanks brighter so the one-way works). This is to stop the group seeing and interacting with the subject fish. Then, we’ll compare that to without the one-way film to see if being able to interact with each other makes a difference.

We are going to place the glass at 45 degrees so the group doesn’t see their own reflections. I’ve spoken to a few firms for advice but they haven’t been able to help, and have said the visual qualities of the films is proprietary – though some publish VLT etc. It would be nice to know the exact visual qualities of the film – e.g. if the films block UV and how much, because the fish we use can see UV. We’d like something as visually pure as possible.

What would be the best solution for this? More specifically:

Would a mirror film provide the one-way vision, but provide more visibility than a black film? Would VLT be the measure that lets us know the visibility?

Whatever we use, there will be some blocking/dimming of light it seems? What kind of film would minimize this?

Is there a company that has a one-way film and a two-way film that are similar in other ways that we could use to match visibility? My worry is that the one-way film will make the groups look darker, so was thinking of using another film to match this darkening in our other tests.

To add another complication, we’re in Canada.

Sorry for all the questions – as you can tell, am new to the window film world.

Thank you!

[Tintguy1980]

17 hours ago, Fish1 said:

 

 

We want to use a one-way coating/film on a piece of glass or PVC so that the subject fish can see the groups, but the group can’t see the subject fish. (So, the group of fish is like the suspect in an interrogation room – we’ll make their tanks brighter so the one-way works). This is to stop the group seeing and interacting with the subject fish. Then, we’ll compare that to without the one-way film to see if being able to interact with each other makes a difference.

Is it just one fish tank, three groups total and you want to wall off 2 groups from one in the same tank?

We are going to place the glass at 45 degrees so the group doesn’t see their own reflections.

If the filmed glass is in the tank they will see themselves as they approach the lower end of slope.

I’ve spoken to a few firms for advice but they haven’t been able to help, and have said the visual qualities of the films is proprietary – though some publish VLT etc.

I don't believe visual qualities are proprietary; sounds fishy. Yes, I had to go there.

It would be nice to know the exact visual qualities of the film – e.g. if the films block UV and how much, because the fish we use can see UV. We’d like something as visually pure as possible.

Practically all films have visual qualities similar to glass itself save opaque or translucent film products.

What would be the best solution for this? More specifically:

Would a mirror film provide the one-way vision, but provide more visibility than a black film? Would VLT be the measure that lets us know the visibility?

There are film products that mimic the interrogation room glass; they are known as 'dual-reflective or DR'. They are shinier on one side in comparison to the opposite side. What would be most suitable for your needs is a dual-reflective that has a VLT of 30%, 15% or 5%. Mirror side of film, of course, faces the subjects.

Whatever we use, there will be some blocking/dimming of light it seems? What kind of film would minimize this?

As long as the light on the subject side is far brighter than the group side, the group will see the subjects but not vice versa. Outside sources of room light may impact the results in a negative way.

Is there a company that has a one-way film and a two-way film that are similar in other ways that we could use to match visibility? My worry is that the one-way film will make the groups look darker, so was thinking of using another film to match this darkening in our other tests.
You may have to experiment with the different VLT films previously suggested.

 

To add another complication, we’re in Canada. AND? There are film suppliers all across Canada.

 

Sorry for all the questions No worries, this is one of the most interesting approaches for film use in my entire career I left 8 years ago. It's up there with: Can I film my bath tub to change it's color. – as you can tell, am new to the window film world.

 

Thank you!

 

 

I have attached a picture of what my mind conjured up as to placement of fish and glass.

[Tintguy1980]

If I misunderstood the placement of group and subject in the picture, please let me know. Seems my posted image is the layout but my words answering the lighting question is reversed. According to what you seek the image is what you go for in set up; mirror side toward the group with increased lighting on the group; lower on the subject side.

Also, window film absorbs UV up to 99.5 - 99.9%.
 

I am unable to wrap my mind around how the blocking of UV will play out in your experiment, because birds see in the UV range as well, yet they still fly into filmed glass. You would think the UV absorbed by film would create a solid obstruction look, to the point of not seeing beyond.

[Fish1]

Thank you - that picture is what I had in mind, but viewed from the top, and with 3 tanks. Here's a sketch.

 

Edited January 5 by Fish1
(Removed PDF, posting image instead)

[Fish1]

[Fish1]

2 hours ago, Tintguy1980 said:

If I misunderstood the placement of group and subject in the picture, please let me know. Seems my posted image is the layout but my words answering the lighting question is reversed. According to what you seek the image is what you go for in set up; mirror side toward the group with increased lighting on the group; lower on the subject side.

Also, window film absorbs UV up to 99.5 - 99.9%.
 

I am unable to wrap my mind around how the blocking of UV will play out in your experiment, because birds see in the UV range as well, yet they still fly into filmed glass. You would think the UV absorbed by film would create a solid obstruction look, to the point of not seeing beyond.

We are going to run the study like the picture (Condition 1), and then again without the one-way glass (Condition 2). This is to see if the group being able to see and interact with the subject changes things. (This is part of a bigger study where we want to use videos of groups instead of live groups – we found that the fish (guppies) prefer live groups over videos, but aren’t sure whether this is because of the interaction or because the video looks odd to these fish – their vision is different to ours).

 

The reason for worries about UV blocking and so on is that maybe we get a difference between the two conditions not because the fish are able to interact or not, but because the one-way film blocks something visual that is relevant to how they choose groups – e.g. blocks UV, blocks certain colours, or makes the group look dimmer. Guppies use colour and UV in choosing mates - they'd be able to see human-visible light through the film (so it wouldn't look like a solid block), but maybe not see the UV colours on the fish in the group. So we are thinking of putting a film on the glass for Condition 2 that has the same visual properties as the one-way film in Condition 2, except allows two-way vision. But we haven’t been able to find something that would do this - and aren't sure what to look for.

 

 

[Tintguy1980]

Yours is the answer.

 

I would suggest a means of placing a light block on top of the mirror area and at each end. This would keep room lighting from hitting the dark side of your glass. This will improve the subjects view to the group(s).

You already know the higher lighting needs to be on the mirror side.

 

Lastly, the tanks inside glass surface may increase in reflectivity once you blacken out above and ends on the central apparatus. This may require you to provide no lighting to the subject tank.

[Fish1]

3 hours ago, Tintguy1980 said:

Would a mirror film provide the one-way vision, but provide more visibility than a black film? Would VLT be the measure that lets us know the visibility?

There are film products that mimic the interrogation room glass; they are known as 'dual-reflective or DR'. They are shinier on one side in comparison to the opposite side. What would be most suitable for your needs is a dual-reflective that has a VLT of 30%, 15% or 5%. Mirror side of film, of course, faces the subjects.

Not sure I understand here - is DR the same as one-way, or something different? And wouldn't it be better to have the VLT as high as possible so the subject can see the groups as well as possible - e.g. 80%? Or is the VLT for 'looking the other way', so we want it as low as possible so we are sure the group can't see the subject?

 

[Tintguy1980]

3 minutes ago, Fish1 said:

We are going to run the study like the picture (Condition 1), and then again without the one-way glass (Condition 2). This is to see if the group being able to see and interact with the subject changes things. (This is part of a bigger study where we want to use videos of groups instead of live groups – we found that the fish (guppies) prefer live groups over videos, but aren’t sure whether this is because of the interaction or because the video looks odd to these fish – their vision is different to ours).

 

 

 

The reason for worries about UV blocking and so on is that maybe we get a difference between the two conditions not because the fish are able to interact or not, but because the one-way film blocks something visual that is relevant to how they choose groups – e.g. blocks UV, blocks certain colours, or makes the group look dimmer. Guppies use colour and UV in choosing mates - they'd be able to see human-visible light through the film (so it wouldn't look like a solid block), but maybe not see the UV colours on the fish in the group. So we are thinking of putting a film on the glass for Condition 2 that has the same visual properties as the one-way film in Condition 2, except allows two-way vision. But we haven’t been able to find something that would do this - and aren't sure what to look for.

 

 

 

Maybe a clear film would work, it too absorbs UV at the same level as dye, metallized, or ceramic colored film.

[Tintguy1980]

7 minutes ago, Fish1 said:

Not sure I understand here - is DR the same as one-way, or something different? And wouldn't it be better to have the VLT as high as possible so the subject can see the groups as well as possible - e.g. 80%? Or is the VLT for 'looking the other way', so we want it as low as possible so we are sure the group can't see the subject?

 

DR film has metallized film laminated to a dyed film and is same as one way. Effectiveness is regulated by VLT of each layer; the denser the more reflective it gets. This produces VL reflection much higher viewing the metal side of the film (which also has the mounting adhesive counting) as compared to the dye side muting the metal. It produces the one way mirror by lighting adjustment and placement of the shiny side and the density of the metallic particles.

Edited January 5 by Tintguy1980