I cannot advise you on your sickness issue, but I can endorse the angel idea. I have ALWAYS had angelfish and do not tire of them in any way. If you get a group of juveniles and watch them spar and pair off, you will have plenty of harmless violence to entertain you.
Like so many domesticated species, there are now lots of varieties to choose from. I am partial to wilds and wild crosses, but my only advice (consistent with my earlier suggestions) is to get all of one type for a more uniform look. They do tend to hang around together a bit. You could easily keep up to a dozen angels in a 180, depending on other stocking.
Otos do not school in my experience, but their task in a 180 is a large one. I have read that they do like to be in groups though, and this seems to be the case with most species when you think aobut it. That is the glory of a larger tank; you get to keep fish in more natural groupings that they themselves prefer.
Back to the deaths: larger communities of any kind regularly deal with death. Nobody likes it, but it is a part of what we are doing with these tanks, so do the best you can, learn, but do not let it cause excessive sadness.
Last edited by tomfromstlouis; 12-07-2012 at 04:29 PM.