Hi there.. I agree with Lupin.. It's not good at all to have only 2 discus unless they are a mated pair... one will always bully the other and it usually becomes stressed to death hiding in the top corners of the tank to try and escape. This same scenario also happens when you keep just 3.. They are 3 then 2 then 1.. You say they are in a 55 with some angels.. how big are the discus and how big are the angels.. Usually at a small age the angels will be more aggressive than the discus and outcompete them for food etc.. This may also be adding to the stress factor for the discus. .I recommend you put the discus in qt and see how it does.. If she has no qt tank, your friend can use a foodsafe rubbermaid container with a sponge filter and heater to set up qt.. it's not expensive.. I would also slowly raise the temp to 84 in qt..What are the exact water parameters and water change schedule.. Is this discus eating at all..is it clamping its fins... Please give us more info so we can get a better idea what's going on.. but it really sounds like stress to me so far.. Stress then leads to many other problems that lead to death unfortunately. HTH Sue