I'm not really sure if this is a mistake per-say, since it introduced me to the keeping of predatory fish... but when I was a kid the guy at the local pet store told me that an African butterfly fish would just ignore the neons and danios I had stocked in my tank.
I think managed to clear out my tanks within a week xD
My hoplias malabaricus paid $40 bucks a piecs for my 2. Wish I had of got the endli's instead. Thinking about trading them in where I got them from. Agreed that other than feeding time they are boring that's why I have the angels in there.
convict cichlids, bought four knowing there breeding habits, thinking it'd be fun, like a tank full of guppies but bigger fish. Wrong, dont pair these guys up unless you you have something bigger to eat them because most lfs wont take them