Fish1

Thanks both of you for your comments - all good points. Will write a longer reply when I get a chance. The fish are just in these tanks for the tests, so we can keep water temperature stable, and we will have artificial plants etc at the backs so that the fish are more comfortable in the space. We'll line the tanks with something non-reflective (we usually use beige shower curtain), and use diffuse light to avoid reflections, so hopefully that will solve the reflection problem, but we'll have to check with a camera in the water or something what it looks like from the fish point of view. Interesting what you say about when human eye can detect reflectivity - no idea what this is for other animals.

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?

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.

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

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!