The males have a more spear shaped body with more fin colouration, if you have golden variants they have a less red colour to them and silvers have vibrant red (if their cross breed of the colours it could vary)
Both types of males have a yellow/ green colour to the tips of the fins which they use to display = more colour and the larger they are the better breeding stock they are to the females
females tend to be more torpedo like with less colours to the fins, and the golden variants have no colouration at all to the fins.
hope this helps - I’m trying to breed mine, if they do try to breed they'll slightly coil around one another and lay the eggs and fertilise them there and then - their egg scatters and don’t tend to eat the young so you can leave the parents in.