Sounds like possible murder too!!! Not too wise to put 2 same type male dwarfs together in the tank with females, one has to be a loser!!!....also a community tank....and it sounds a bit crowded.
If he has severe gill flukes ...you can see them when his gills close and will just barely show....they like little whitish leeches. Trouble is your other dwarf or any small cichlids can get them too now. If his mouth is stuck open how is he pushing water thru his gills?? If he isn't he is slowly drowning.
Sorry to say it but it doesn't sound like he will recover.
Edit...Heaps of others
If you are new to apistos I strongly recommend that you slow down...Keep the Ram's going. Get a 20 gal long for breeding the Cockatoos...and wait til you get that down. All the Apisto species and dwarf cichlids have different personalities...from gentle to major aggressive....and females with babies can be absolute terrors in a crowded tank. Keep up the research and plan as you achieve success.