bare bottom tanks

[farm41]

I have a couple of 10g tanks that have been using bare bottom. Most of the fish I have put in them haven't really paid much attention to their own reflection, but the male A. hongsloi I just bought seem to spend most of his time staring himself down on the bottom glass.

Is this a big deal?

I'd like him to spend his time paying attention to the female instead of his mirror image. I'm thinking about a black sand bottom, but I want something that is easy to see when it needs cleaning.

What do you do?

thanks

 

[Z Man]

Farm,
I have 75 tanks right now but not one piece of gravel in any. I did buy some tanks from a retired breeder that he had painted the outside botttom with black latex. But now whenever I clean one (they're mostly 15 gallon) lots of paint peels off them. I have also heard of people putting black paper or black cardboard under the tanks. Almost all mine are clear bottom now. I have never had problems very long with the fish looking at themselves.

 

[Charlotte]

A little Physics...

The mirror image that you see looking from the front of the tank is just an "optical illusion." If you put on some goggles and look into/through the water and down from the fish's perspective, you will barely be able to see yourself, just as you can kind of see your image in a clear window. Only someone standing outside the tank will see the mirror on the bottom.

It looks like a mirror to you because of the different indexes of refraction in the different materials. When the light passes through and one material has a higher or lower index of refraction, it causes the light to bend. The reflection you see is because of the light bending. If you want a more detailed explanation, I will have to drag out my physics book and look up some details, but I can if you like.

I think that the fish might see a mirror image from in the water, but I think that it's only looking up at the surface of the water from underneath. (I'm not sure...) I think they will see out of the water directly above them, but as you move further away from straight above, it will become like a mirror too. So they kind of have a circle-shaped window in what looks like a mirror on the water surface above them. I'm not positive about this part, though. I could be wrong. Anyone done any diving that could enlighten us on this one??

Hope this helps. I know my fish try to get out through the bottom if they can see through to the floor, so I just tape a brown paper grocery bag to the outside of the bottom, and they seem to accept the boundary a little better that way.

 

[farm41]

I don't know about the physics of light bending and such, but, it was very obvious that the male was fighting his own image. He was swimming along the bottom nose down turning all sorts of ways trying to get to the image he saw. The conformation for me was immediate when I covered the bottom with 1/2" black sand, it was all over, he has completely changed and doesn't fight the bottom glass anymore.


Thanks for info