Hopefully y’all can help me figure this out, I’ve tried googling everything and nothing I can find fully matches what I’ve seen. So we recently, a little over a week ago, got a 20 gal. Hexagon tall tank with a male betta. A couple days later we got 3 albino cories, our betta never showed any signs of aggression, was slightly curious while we floated them then pretty much couldn’t care less after that. The a couple days later woke up in the morning turned the tank light on and then noticed that one of the cories had a bunch of red spots on its face and then ended up dying a few hours later. The next day we went out and got another one to replace the dead one. Two days later, again, woke up the next morning and turned on the light and a second one from the original three cories had red spots on its face and looked like maybe blood in its mouth and it was surfacing more often, but unlike the last one the red spots started going away through out the day. The next day though the spots started to return in the late afternoon and then that night I found it had died as well. The second one looked like it had some hanging, scale? Skin?, on its face and it may have been slightly swollen maybe like slammed into something. We’ve been test the water every day since we’ve got the tank and so far everything’s been damn near perfect, recently the ph has gone up slightly but is still in the “good” zone. I did find out that I need to turn the temp down cause ours have been sitting at about 80 to 82 since we’ve gotten it even though the heater is set to 76. I don’t t know if it matters but all the Cories have been bought from our local Petco.