Don't worry about pairs, they will be given their own tanks as necessary as I said in my original post. I'm intending to raise some fry from the Festae, they are one of my favourite fish. At the moment, my male is less than 2/3rds of the size of the female and they haven't paired off. They show no signs of interest in each other at present, in fact, she bullies him and won't let him near her! He is within reason the only bullied fish in the tank. I can't wait till they pair off. Their colours really pop when they breed.
Anyway, I'm going off subject. Would an eel otherwise be suitable taking the Festae pair out of the equation.
Any other rare and unusual oddballs you can recommend? I don't really want to add anymore cichlids, I want some other types of fish to break it up a bit.