Originally Posted by Help BLUE
and recently I noticed
Do you keep him in a back room and not look at him?
Im sorry, but things like this, they do not
happen over night... Or even in a few days.
I would run him on a gram neg and positive medicine sched. for a while, to aggressively get rid of the rot (gram neg) and then cure any secondary infection that might be gram-pos.
Clean water, moderate temps and water changes according to the dosages on the boxes will put him right.
Honestly, though, considering his age and how awful this looks, he might just not be able to handle it... The older they are, like in people, the harder it gets for them to recover.
I would suggest meds like maracyn I and II used together for the recommended full dose and time, and once that's over using moderate salt treatments (up to 2tsp/gallon) and vigorously clean water, along with high-protien foods (upwards of 45% or live foods) to help him regain strength.
This is in no way ich, of course, and its not a fungus... its just rot, and awful rot at that. Once he's better or in future with another fish, please look at how to care for them adequately with frequent enough water changes, as this is how rot usually occurs-- from lack of sufficiently clean water.