So I just did a 30% water change, moved the rocks, and cleaned the filters. After the water cleared I went to take a look at my fishies when I noticed the guppy had a weird discoloration on top of his head. It's kinda dark and mossy looking with a clear like patch of randomness, it doesn't look like it has legs or anything, but then I noticed his mouth looked funny with a sort of white spongy material. I thought maybe he is just a messy eater, then I noticed a couple other of my fish seemed to have the same discoloration atop their heads....and I noticed a different swimming pattern, like they were rubbing something off.... so I could use some help identifying the problem, if there even is one. The first pic is the guppy, then the second is my Lab. the lab has dark areas more so around the area in front of his Dorsal fin. then the rest of the pix are of the other ones I noticed a dark discoloration around their faces.... I also have video of their behavior and discoloration...