Will my fry eat brown algae?

[joidevive]

I have zebra danio fries that just started swimming in 10 g. I was planning on letting them eat what microbes are there. There’s small brown patches on the glass of the the tank. And I also have a small java moss - not sure if it has enough Infusoria though.

 

[joidevive]

Update: I see my fries are pooping. There must be plenty of microbes growing in my tank that they are eating. My java moss is only the size of a golf ball though.