The eel scales are small and oval. The fish has so-called round scales. These are embedded in the very thick and slimy skin of the fish.
Certain species do not have eel scales
In addition, certain species may have completely scaleless skin. This is the case, for example, with conger eels (Congridae), snake eels (Ophichthyidae), snow eels (Nemichthyidae), black deep-sea eels (Cyematidae, Cyemidae), white eels (Myrocongridae) and knife-toothed eels (Muraenesocidae).
The coloration may vary between black and dark green on the surface of the eel. The underside varies according to the age and life stage of the eel. The underside of yellow eels, in the phase during which they live 4 to 12 years in fresh water, is usually yellowish.
In the adult and fully grown silver eel, the underside is almost completely white when it returns to the Sergasso Sea. If you are looking for more information about the eel and its scales, here is a very good book: AnzeigeDer Aal