What is the difference between male and female piranha?

They're is several things that make male goldfish and female goldfish different -Male goldfish are smaller than female goldfish -female goldfish will have a rounder body when the male has a slimmer looking body -males will develop breeding tubercules on their head,gills, and fins during breeding season-male goldfish may chase a female goldfish's rear -males will have more pointed fins when females have rounded fins instead