I have had this dresa for about 6 months, very large... 20lbs. Beautiful animal. Did some fragging in tank(75g) and left glass tops off during the night(3/9). Didn't notice temperature was down until next evening. Temp dropped to 78 degrees (3/10). Everything in tank looked fine but the clam was receeded and sloughing off. Determined tank was cold, added another thermometer, put glass tops on, and checked water quality. Everything was right where is was supposed to be. I guesss the shock was too much for it. Today it no longer responds when lights are turned off or on. It was close to tearing from stretching so far so I tied fishing line around the back side to keep it from falling apart. I don't want it to suffer any more. It's killing me to watch it die. I don't have a camera to show you how bad it looks. It is still breathing in and out. I have done a 5g. water change the last 3 nights. changed carbon twice this week and keeping skimmer cleaned...which is picking up a lot of foam as of now. Tank is cloudy but ph=8.0, nit=0, ammon=not a trace (wasn't able to do nitrate out of a solution) Running diatom powder to clear up tank to keep and eye on it. I don't want to crash the tank. When this animal dies....does it just go flat or what? Does it disentagrate? At this point I know there is no return...what should I do for her? Thanks for your input.