hey just wondering if anybody had a sure fire way of identifying female and male serpae tetras? ive heard that ones a brighter colour and that the females have more white on the bottom fins but all mine seem to have white on their bottom fin and two of them have a biger top fin (more fanned out) then the other one - is this also a sign?

i absolutly love these tetras as theyre so playful and would like to start breeding them