There are different things to look for in sexing rams and you can't go by just one typically. Due to these fish being bred in captivity in an attempt to make them as colorful as possible they are hard to sex. Males typically have a pointer tip to their dorsal fin as well as a significantly longer second ray in their dorsal, they also tend to have a yellow gill plate with the color extending into the belly area. The males also typically have a red mouth/face and also have a larger black dot that doesn't have the metallic blue sheen to it. Females typically have a pink/red belly and metallic blue sheen in their black dot, also females tend to be more lean and makes tend to grow more round. The females often have an extended second ray in their dorsal fin it's just slightly longer than the other rays but significantly shorter than that of a male.