The Skin And Scales Of A Fish
All fish have a skin structure that consists of scales and a slimy substance called mucus. There are many different kinds of scales, though the two most common on fish are cycloid and ctenoid scales. Cycloid scales have a smooth rear edge on them, these scales are found on fish like carp, herring and tarpon.
Ctenoid scales have a brush like rear edge, found on fish like perch, bass and walleye, the scales are shaped like a fingernail and overlap one another.
Even fish that seem to have no scales at all, actually do, like the north American eel. The eel has a soft slimy scaleless feel to it, but in fact it does have scales which are very small and mucus covered.
The skin and scales of a fish serve to protect the fish from injury and infection. The mucus which is found on fish protect the fish from invasions from bacteria, parasites and fungi and also helps to repair open surface wounds. The mucus also helps regulate how much water is absorbed by a fish.
