Open and enflamed - red gills rapid breathing carpintis

[sodas]

Hello everyone.
I m having this issue .
My carpintis the last few days is just
standing in a corner of the tank refusing to eat.
His gills are almost wide open and i can see his inside is deep red.
He s also fast breathing.
He s housed with 2 synspilla a male sajica and a blue acara in 125 gallons
The rest of his mates are doing fine.
I m doing 50% water change every week with substrate vacuming .
The filter is an eheim 2080 and i got it cleaned a couple of weeks ago.
I m 100% positive it s not a water issue .

Anyone knows what this might be?

Thanks in advance
http://imgur.com/W8TQMXw

 

[Charney]

sorry we need some of the basics. Water parameters? is he getting bullied? How long have you owned him? any new additions in the tank? Can you get him into a qt or divide him so the other fish don't go at him?