Salmon have six bony fins on their body, which they use mainly for balance and steering:
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two pectoral fins near the head,
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two pelvic fins on the belly,
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an anal fin behind the belly, and
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a dorsal fin on the centre of the back.
Salmon also have an adipose fin, a small fatty fin on the back just in front of the tail, with no known use.
The tail, also known as the caudal fin, helps the fish keep balance, and pushes the fish forward through the water. Female salmon also use the tail to dig the redd in which they lay their eggs.
Like most fish, salmon have a line of special cells along each side of their bodies. The cells, known as the lateral line, are extremely sensitive to pressure, and help fish sense movements and objects in the water.
Scales and skin cover the body of most fish, including salmon. Scales are small hard plates like fingernails, but they overlap like shingles on a roof and protect the fish from predators, as well as from bruising. Scales begin to grow when the salmon are very young, and show annual growth rings, like trees. If scales are knocked off, salmon can grow new scales. Salmon and many other fish also have a slime layer that makes them slippery and protects them from disease organisms in the water.