Help! Algae id?

[gu2high]

I have this brown algae problem on the rock and plant. Ottos do not touch it. The tank is old. So it is not diatom. Is this a red algae? But the color is like iron rust to me, brownish, not red at all. Or a cyanobacteria? Need id it. Thanks!

here is the picture,

 

[Zezmo]

Sure looks like regular brown algae to me. It is not Cyanobacteria.
The otto's might not eat it because the rock is rough and hurts thier little mouths.

 

[gu2high]

The algae is on glass too, and it is easy to wipe it off. I remember when the tank was set up, there is a diatom/brown algae problem. When I bought several ottos, they cleaned the tank within three days. Are they get lazy now or eat too much the brown algae and tire of it?

 

[theotheragentm]

All fish get spoiled on supplemental foods and may not do a great job cleaning up after a while.

 

[Purrbox]

My guess is that the otos are getting enough to eat elsewhere, and therefore not interested. From the description and picture it definately sounds like diatoms, which while less common in established tanks does still crop up from time to time.

 

[gu2high]

Thanks, if it is diatoms, it is good news to me. I like ottos and are going to add more ottos to the tank.