Koi swimming upstream represent perseverance and strength against adversity, drawn from the legend of the carp that climbed a waterfall and became a dragon. In Japanese tattoo tradition they also carry associations with good fortune and ambition. Rendered in black rather than colour, the design leans more into bold graphic strength than the luck symbolism often tied to red or gold koi.
Where it sits
This is a tall, curving vertical composition, so it suits the forearm, calf, or spine where the body's natural length matches the fish's upward twist. It could also wrap a thigh given the width of the tail fins. Shrinking it down would blur the fine scale linework and the wave detail at the base.
Making it yours
Ask an artist for any of these.