There was a Japanese legend about Koi fish that if a Koi successfully climb the fall on the Yellow River at the Dragon Gate, it will transform into a dragon. For that reason, the Koi symbolizes the strength, courage, determination to overcome obstacles and ability to obtain higher goals in life. Other say it means good fortune or luck.
There are many different opinions, though, to the symbol of the Koi Fish Tattoo. Some people feel that there is a sexual symbolism to the color and the direction of the Koi swim. There are also sources that said Koi is a symbolism of family where a black Koi represent the father; orange/red is mother; blue/white is for boys; and red/pink is for girls. For me it's a great choice of tattoo for both men and women because not only it gives a perfect shape on the arm, koi fish tattoos are popular for the deep history and symbolism behind them.
A Koi sleeve tattoo is supposed to represent many different things depends on how you see it, what color it is, or the direction of the Koi swimming upstream. Some say having 5 golden koi tattoos on your arm is a symbol of wealth and well being.
The best place for having this Koi fish tattoo is on your arm where the fish and water designs could fit perfectly and look like it's swing up stream your arm to the shoulder. I have many friends who arms are tattooed with Koi fish designs and let me tell you, it is one of the most colorful and sexy arm I've seen.