My Fish Are Dying Off!

[Boston-Celtic]

G'afternoon everyone. I have this bit of an emergency. I have a 55 gallon at home with a pleco and 15 cichlids, mainly peacocks. One by one my cichlids have been dying off, so far 3 have died. I know that they arent being killed because they have their eyes in tack and show no damage to their fins or body. Before dying I do notice a change in their behavior though, they seem to try to stay in one spot and move the least that they can. Also they seem to be breathing heaving, opening and closing their mouths faster then normal as if gasping for air. I dont know what is wrong with them but I did apply some fungal and bacterial medicine, removed the carbon filter and increased aeration. If anyone can help me out with some suggestions or something I would greatly appreciate it. Thank you.
 
Sincerely,
Anthony

 

[StevenF]

What are your tank parameters Ammonia, Nitrite, Nitrate, GH, Kh, PH. water temperature.  As of right now Ammonia and Nitrite are the most important to know.  If they are high they will cause the symptoms you see.  How long has this tank been set up?  If it is new did you cycle it with Ammonia before adding the fish?