FISH AND SHELL-FISH AS FOOD 173 



glycogen, or animal starch. Some of this carbohy- 

 drate is also found in crabs, lobsters, and other 

 crustaceans. 



Fish differ greatly in their fat content. Not only 

 does the average fat content of the various species 

 of fish vary widely, but there is a definite seasonal 

 variation in many species, and even the individual 

 fish of a school caught at the same time contain 

 different percentages of fat. Certain species of fish, 

 however, are always lean, whereas others always 

 contain much fat. Still others of medium fatness 

 usually contain four or five per cent of fat when 

 fresh. The more common fatty fishes are the mack- 

 erel, Spanish mackerel, herring, sardine, salmon, 

 butter-fish, alewife, eel, and shad, while the more 

 common lean sea fishes are the cod, cusk, haddock, 

 pollack, hake, flounder, grouper, sea-bass, red snap- 

 per, and tomcod. 



Curiously the protein content of various fishes is 

 nearly constant, for as the fat content of a fish 

 increases its moisture content decreases. Thus the 

 consumer gets more food for his money by buying 

 fatty fish, in preference to lean ones at the same 

 price. 



In general, the composition of fish is approxi- 

 mately the same as that of meat; both are high in 

 protein and have a variable fat content. The com- 

 position of fatty fish may be compared to that of 

 the fatter cuts of pork, and the composition of lean 

 fish resembles that of beefsteak. In many cities pro- 

 tein may be purchased for less money in the form of 

 fish than as meat. 



