Hello all. About a week ago, I noticed that one of my malawi cichlids was swimming unusually in the corner of my 75gal tank and seemed as if he was stuck in the corner. He was swimming almost vertically with his head towards the surface of the water and wasn't moving his fins much at all but didn't seem to be attempting to get air or anything of the sort and this was the first time that I had noticed this fish or any of the fish in my tank acting this way. My tank is fully cycled and has been running for a while now doing around 30% water changes about every 2 weeks. I feed the fish Omega One Super Color Cichlid Pellets two times a day. I became very worried about the fish and expected him to die and wasn't sure whether this issue was contagious or not within the tank so I removed the fish and put him in a 26 gallon bin full of water which was the same as the tank water and he seemed to swim fine in that water with no other fish around. Unfortunately after I had performed a water change on the bigger tank and put this fish back into the 75 gallon tank, he was acting just as before I took him out of the tank again. Then when I came home today I just noticed that another one of my malawi cichlids was doing the same thing. Does anyone have any idea what the issue could be. Aggression within the tank maybe? There are plenty of hiding places for all the fish in the tank but would like to keep them from dying. Thanks!!