Black Beard algae
I have a 9 inch plecostamus that loves the stuff.
It only seems to grow on one plastic plant, which I debate removing, but he
loves it. (Eating it right now)
Aside from physical removal I don't know any easy treatment.
Florida Flag fish sometime develop a taste for it.
I use Java Moss to remove nutrients from the water. I don't often have
treouble with any algae one I add Java Moss