From Science Magazine.

Ten seconds before it charges, a marlin "turns on" its stripes. Then, when the attack is done, the marlin dials the contrast back down. Layers of colorful cells in their skin rapidly change shape to create the strong pattern.
Read the article: https://www.science.org/content/article/watch-marlin-flash-bright-stripes-deadly-strike
Footage: Alicia Burns
Script: Sierra Boucher