Strange dots on Bubble tube

[Fordaz]

I just noticed today a bunch of weird orangy-brown dots all over the top part of the inside of my bubble tube, and I havn't a clue what they are.

Interestingly, I found one of my Danios had died also, so I'm wondering if they're related.

They look similar to a picture I saw in another thread which people thought looked like aborted fry, the dead Danio was really fat, and I think it may have been pregnant (although, I was under the impression they were all male).

Take a look at these images, the zoom view isn't great quality, which I apologise for.

Bubble Tube (56k beware)
Bubble Tube Zoom view

 

[Sky042]

looks like algae.

 

[Fordaz]

Why's it brown?

 

[tstenback]

Not all algae is green. There are green, brown, red, black and combinations of these. There may even be other colors but these are the most common types. HTH