A floating organic film is typically called the 'protein layer'.
There are many fish which actively consume this, ie: all livebearers.
Biofilm is what makes underwater stones in a river slippery to walk
on.... well, that and algae : ) Biofilm is mostly colorless, so a
brown coating would also have diatoms, a green coating - algae, a blue-
green coating - bacteria, and a red coating - algae and/or diatoms
though usually you have one or the other since they prosper on the
opposite light intensity extremes.
NetMax
On Feb 12, 11:45 am, "pH7, Aquarium Ninja" <
p...@aquariumninja.com>
wrote:
> At the beginning of last December I snapped this photo (see link below) looking into my aquatium and upward to the surface. At the surface I saw this rainbow coloring and a thin, milky white, translucent film-like substance. I was able to clean it out with paper towels and surface skimming with a siphon. It was slippery to the touch, and appeared to be some kind of organic matter that one over time. It was about two weeks into a fishless cycle for that aquarium. After this cycle completed, I cleaned the tank again and introduced fish. The film-like substance has not returned.
>
> I always wondered what it was. Now that I have a bit of spare time, I wanted to share the photo and ask all of you, is this what we commonly refer to as biofilm? What does it look like to you?
>
> PHOTO:
http://s1204.photobucket.com/albums/bb402/aquariumninja/Biofilm%20Or%...