A 15 is on the small size for them, but you might get away with it. Have plenty of hiding places and caves/flowerpots/,coconuts.
If I remember correctly, P taeniatus is one of those fish where the sex ratio of the fry is linked to pH. Some people try to get just the right pH, and others will raise a batch of males, then change the pH and raise a batch of females.
If you haven't kept kribensis, you might want to try a pair of them first to get some experience. The other species are less domesticated.