Is it Fungus,Bacteria,Protozoan or Flatworm Platyhelminthes?

[Shadi]

Since ten days one of my Oranda goldfish start scratching against tank decorations, four days later I noticed a large dark red spot on the lower caudal lobes, and since yesterday all my Oranda fish stays on the bottom of my tank, they move only when I feed them, I found transparent feces floating on the surface today morning.
I changed 50% of the tank water, temp 78F ~ 26C, PH 6.8, fish still on the tank bottom.
Please advice me how do I treat this Disease?

[rollie]

don"t have fungus. got the bacteria, unsure of it name, dut seen it before. treat with pimafix and melafix, those should heip.

[DemonShark]

also i read if you raise temperature itll help the fish