Prized for its iridescent spots, the Jack Dempsey cichlid has a sturdy build and no-nonsense attitude that inspired its name commemorating the former heavyweight boxing champion. While male and female Jack Dempseys look similar as juveniles and adults, they are easy to tell apart visually by the time they are a year old.
Turning the Other Cheek
The most reliable way to tell male from female Jack Dempseys is to check their cheeks. Males have bluish spots directly behind their eyes, with no spots on the lower part near their mouth. Markings on females extend the full length of the cheek with large iridescent blotches on the lowest part of the cheek. Another way to tell is to look at the tail fin. Males have pointed edges to the tail fin, where females have rounded edges. The anal and dorsal fins also are pointed in males and rounded in females.
Getting in the Fight
Determining sex in juveniles is much harder and even close examination of a fish's vent openings is unreliable until they reach sexual maturity. However, male Jack Dempseys tend to be more aggressive toward other males even before they are fully sexually developed. If you suspect you have more than one male in your tank, remove the extra males or they will continue fighting until only one remains.