Gather the hair on top of your head to create a high pony at the crown area, and secure it with a hair elastic. Divide the hair inside the ponytail into two equal sections.
Take a small section of hair from the outside of the right section, and bring that section up and over into the left section. That piece is now a part of the left section.
Repeat on the opposite side, taking a small section of hair from the left section and crossing over to the right section.
Continue the fishtail-braid pattern until you get to the ends of the hair and secure them with a hair elastic.