Rams, rams, rams
I have kept Oscars, JD, Firemouth, various common Africans (yellow labs, etc), and Discus. Rams seem to hide out, I have to struggle to find them, then bones are the next thing I see (usually under the pleco's mouth).
I would love to have them again, but just can't. I even had a double red apisto which was not too cheap, and he lasted a week.
I am not sure if they just have a hard time acclimating or not - seems to be a "not eating" thing as I never saw them actively go for food, doesn't mean they didn't get leftovers though. Hmm