The mature males will undoubtedly grab a cave to hide in, but what you must remember is that we think of caves as a slate or ceramic tunnel, whereas a zebra will think of it as a dark place just big enough for it to cram itself into. What this basically means is that the mature males will find a spot to call there own territory, and these spots tend to be caves as they are areas tat can be protected.
The females however will still form territories but these as less specific to a particular area and less well defended. i.e their territory would be to one corner of a tank.
One of the reasons it is difficult to sex a younger fish by this method is because they do not tend to be territorial until they are sexually mature. They will most likely just try and find the safest place to hide, which could be a cave, a lump of bogwood or quite simply some slates!
