Koi mean strength, perseverance, bravery, transformation. In the legend, they swim upstream, over the waterfall, through the dragon gate, and then turn into dragons.

You can have your koi swimming up or down the arm. Swimming up means the struggle is still on. Swimming down means you’ve reached the goal. But honestly, I think the best way to decide is where you want the koi’s head. You can put a lot of meaning into how you arrange things and it’s good to understand that. But the most important thing with any large tattoo is that it looks cool and has good flow. That matters more.