red tailed shark

[shanklyred]

my red tailed shark had a small white patch on the rear end just before his tail. Now it's getting bigger, and looks like an open wound.i'm treating the tank for whitespot, as my clown loaches look like they're covered in salt. it doesn't look like whitespot though?(on the shark) has anyone got any suggestions?

 

[Zagz]

Is there anything in the tank that would have caused the spot by injury? What size tank and what inhabitants? If a large tank I would QT him and treat with melafix and pimafix for starters. Can you get a picture?