sexing keyholes

[piranha]

I raised 6 keyholes and removed 4 when 2 paired off. Contrary to what I've read that the males have longer fins, darker coloring, and are larger, I've found this to be untrue. Maybe there is no accurate way to determine sex.

 

[Voodoo Chilli]

Keyholes are tough to sex. The males being larger, with longer anal fins provides a decent starting point for determining sex but your right- it's not 100% reliable.