Do all koi fish have whiskers?

No, not all koi fish have whiskers. Whiskers, also called barbels, are sensory organs that help fish detect food and navigate in their environment.

While many koi fish do have barbels, there are some varieties that do not. Specifically, the "Doitsu" type of koi, which is characterized by a lack of scales, are typically bred without barbels.

So, while most koi have them, it's not a universal characteristic.