Eel skin. Light micrograph of skin from an eel. The eel is a fish that has extremely small scales embedded in its skin. Fish scales arise from the skin of a fish. They are made from dentine, and are similar to teeth and hair. An eel's scales are arranged in small groups. In the near-absence of scales, mucus is secreted to protect the skin. This makes eels very slippery to handle, hence the phrase 'slippery as an eel'. 'Eel skin' leather, despite its name, is not from eels, but from a different fish, the Pacific hagfish.