Koi whiskers are pretty easy to spot. They are located on the top and bottom of their mouths. They have been known to be different colors including brown, white, and black.
Koi actually have two sets of whiskers. The first set is usually near the top of their lips. Typically smaller in size and could resemble growths more than whiskers. The second set is usually around where their top and bottom lips meet.
Whiskers help koi with a few different things: they koi sense and taste food, actually, by sensing the chemicals in the water.
Surprisingly, koi are actually born without whiskers. When they are a few weeks old their first set of whiskers will grow in. But, they are only temperary and will actually fall off in a couple of months.