We have had great success with our two DP's and three emerald green Cories. The cories stick together and the DP's don't ever seem to notice them. In fact, our male DP, Rocky likes to hang out in the castle during the day, many times you will see him along with all three cories in there together. Mind you that we bought all five fish and added them to the cycled tank at the same time (within a day of each other). It has now been 11 months since we bought them.