The size of the whitefish in the Great Lakes is not so great as the extent of water would indicate. Probably three pounds would be an average size, although the individual fish range from 1¹⁄₂ to 6 pounds. The weight rarely, however, exceeds 4 or 5 pounds. Occasionally whitefish have been found weighing as high as 20 pounds, but this is very rare. The whitefish reaches its full average size about the end of the fourth year. The number of eggs which are found in the female fish is not so large as in the shad, but usually the number does not fall below 10,000 and sometimes reaches as high as 75,000. The eggs are very small comparatively, and about 36,000 of them make a quart. The U. S. Bureau of Fisheries has done a great deal to increase the supply of whitefish by planting millions of whitefish fry in suitable water. _Different Species of Whitefish._--There are many species of whitefish besides the common whitefish which appear in the Great Lakes. Coulter’s whitefish is found in the waters of British Columbia, but it is not distributed very widely throughout the country. The Rocky Mountain whitefish is very widely distributed, occurring in all suitable waters from the west slope of the Rockies to the Pacific. There is also a subspecies of this fish occurring in the headwaters of the Missouri river. Menominee whitefish occur in the lakes of New England, New York, and the Great Lakes,--it is also known as round whitefish, frostfish, shadwaiter, pilotfish, chivey, and blackback. _Composition of Whitefish._-- FRESH. DRY. Water, 69.83 percent Protein, 22.06 „ 76.00 percent Fat, 6.49 „ 21.51 „ Ash, 1.62 „ 5.36 „ _Average Composition of Fish._[16]-- Water, 76.06 percent Solids, 23.94 „ Nitrogen, 3.51 „ Phosphoric acid, .52 „ Sulfur, .24 „ Fat, 1.45 „ Ash, 1.21 „ Protein, 21.92 „ [16] Average analysis of cod, halibut, bass, etc., used at the hygienic table of the Bureau of Chemistry. =Fluorids in Fish.=--Nearly all kinds of fish yield a distinct test for fluorin which is not to be mistaken for an adulteration. The fluorin is found normally in the bones of the fish and sometimes in traces in the flesh. The addition of fluorid as a preservative is highly reprehensible, and its presence is indicated by the increase in quantity.