Pleco or fungi... remove pleco & salt. Generally ray bites are around the disc where the other ray gets a chance to grab a quick bite. If you have rays that are getting bit on the top from other rays it means the ray is ill & won't move out of the way... not good...
Funny?
my female had 3 healthy litters after getting bit up like that each time.
the bites were above the tail and along the sides of the body and not the disc edges.
