Whats This? Dwarf Gourami Mucus?

I have 2 dwarf gourami’s and they seem to “spit out” this substance, I have no clue what it is.  Its like a slimy/mucus-y stuff, always with a little food chunks mixed in.  Does anyone know what this is?  Its always all over my tank, mostly at the bottom, around my plants, or any object, though it seems like they “make it” up at the top of the tank…
 
I have attached a pic of it, though its not a good one as I just cleaned the tank last night, and this is what they were working on this morning…