Please explain what is going on for me. I have a 150 with (1) 5 inch temensis, (1) 4 inch broko, (2) 4 inch orinos, (1) 6 inch kelberi, (1) 4 inch Azul and a 7 inch tigerfish. I do a 50% water change weekly and the water conditions are always good. I add salt to the tank and the water parameters do not really change noticably before and after the water changes. My question is, after each water change, the temensis and the azul will always seem to have issues with their gills. They breath alittle heavily (nothing alarming) but seem to constantly try to cough out something from their mouth. They will shake their head alittle as well when they seem to be coughing. They will do this for about a half hour to an hour. Mean while the other fish act as if nothing has happened, and will immediately beg to be fed once the water change has taken place. After an hour or so, the temensis and the azul want to be fed as well. Has anyone seen this in the past or have any idea what is going on with those 2?