Hi Creat. He's a handsome boy! I love his coloring. Fortunately, I don't see any signs of the mystery disease so we can rule that one out right away. (WHEW!) Also, his fins still appear full and not clamped so he must be feeling more or less okay. Aside from the discoloration and the rip, is he acting all right? Eating and active? No more discolored spots?
It's possible he took a chomp out of his tail himself although usually it doesn't bleed like that. His fins may have been weakened by a mild bacterial infection or possible flukes. Conservatively, you can treat him with AQ salt at 1 tsp per gallon and a product like Stress Coat or Kordon Fish Protector. If he's acting pretty much like himself, this is probably the best route to go so we don't medicate him if it's not necessary. Too much and the fish will eventually develop a resistance to the meds.
If the tear fails to heal, stays bloody or turns black, or if his behavior changes, then I'd suggest the Kanaplex.