i think my fish is dying please help, jack dempsey?

[Hollie]

the best way to tell you what he is doing, is its like he is choking or gasping for air. The pet store that i got him and his mate from they have had him for about 3 mo. and i would come in every week and see them, trying to make up my mind that i wanted them so i now if has nothting to do with the pet store, he was fine till he came here. he and his mate our in a 125 gal take along with a 6in oscar and a 7in alge eater. he is not closing his mouth at all and is full exstending his gills, very labored. he was doing this when i took him out of the bag from the store, he was only in their max 20min. 5 to home and 15 to get ajusted to the water temp before releasing him. i'm trying to give evey thing i know that it make trigger something from some one. please help i really think he is dying