Well they are Monomorphic
http://www.cichlid-forum.com/articles/l_ocellatus.php
The primary difference among the sexes is that males are almost a half-inch larger than their counterparts. Males max out at 2 inches (5 cm) in total length and females at 1.5 inches (3.5 cm). Other differences are more subtle. Coloring is identical except females are supposed to have white-tipped dorsal and anal fins, whereas males' are gold. Males also tend to be more territorial than females, unless the latter are tending a brood. For example, females will usually let other females pass through their territory, although a visitor is often greeted with raised fins and only sometimes is chased off
Males, on the other hand, will chase off
ANY intruders, even non-cichlids. I'll never forget the time I first introduced a pair of 1.75-inch
Synodontis multipunctatus in with the ocellatus. One of these cats aimlessly wandered through the male's territory and made the mistake of coming within an inch of his shell. He didn't injure the cat, but this male mercilessly attacked it until it retreated to a piece of holey rock. These two cats have learned that while they are free to cruise through the females' territories (unless they're guarding young), they are not permitted to go within 3 inches of the male's shell.
Males also tend to be a bit more elongated and females will round up around the belly region when conditioned. Females will spawn every six weeks if kept in good condition.