Just my personal experiece, I had a mated pair of Clarkii's, and was given a falce perc by someone exiting the hobby. I warned them I had no place safe to put him, but they wanted out, so I put him in my main tank with the Clarkii's. (This was before I discovered this board or he woulda found a different home!)
The Clarkii's, mainly the female, harassed and killed him almost immediately. I didn't have a chance to even try to get him out...
Just my experience, as with all things, your mileage may vary...
