after some trial and error i am finally able to keep P. Altums and not kill them. They come naturally predisposed to a disease that eats their fins and causes a nasty fungus just before it kills them.
one person successfully warded off this disease with methylene blue, i've seen on other forums someone has used a medication called Foran-2.
once i figured out what was happening i added salt to their tank and i brought the temp up to 86 degrees F (this is the first thing i try when any of my fish are sick). and when i saw nothing change in 2 days and had 2 more dead angelfish, i did a BIG water change, 75%, and replaced the salt, then added pimafix for 7 days, just like the bottle says, and did two 25% water changes 2 days apart and then treated with pimafix again.
i have 3 altums left, one with virtually untouched fins, one with just the tips gone, and one that i just barely brought back from the brink, has almost no fins and was starting to get the fungus stuff when the pimafix started to work for him. His fins are starting to grow back, and he's doubled in size now. the one with no fins is actually the dominant fish in the tank.
when i get more altums i will NOT put them in this tank to start with, i will put them in a smaller tank and treat them with either pimafix or Furan-2 before they are introduced to this tank with my now healthy altums.