6 U. S. BUEEAU OF FISHERIES. 



At 3 years the average weight should be about 1 pound. It is 

 probable that fish under congenial artificial environment, receiving 

 food regularly, will somewhat exceed this rate of growth. Because 

 of the flavor and fine quality of its flesh the brook trout is highly 

 esteemed as a table delicacy, and, as it is very game, it is much 

 sought after by sportsmen. Those from clear, swift streams do 

 not grow as large as those found in quiet and deeper waters but are 

 superior in quality and appearance. 



FOOD. 



The brook trout has a voracious appetite and takes advantage of 

 every opportunity to satisfy it. Some observers believe that brook 

 trout do not feed during the spawning season. This may be true, 

 in a measure, of wild fish, but fish that are kept under domestication 

 and regularly cared for continue to feed throughout this period. 

 In the wild state the species is no doubt largely carnivorous, its 

 food consisting chiefly of Crustacea, Mollusca, and various forms of 

 insects and worms. When pressed by hunger, it does not hesitate 

 to devour its kind. Under domestication, however, it can readily 

 be induced to eat mush made of various cereals. Kendall (loc. 

 cit.) has the following to say regarding the feeding habits of the 

 brook trout : 



The trout seems to avail itself of whatever animal life is available, and vege- 

 table food is not always eschewed. A detailed list of what trout have been 

 known to eat would be more astonishing than valuable. However, the general 

 and principal food supply upon which the adult fish depends may be divided 

 into two classes — fishes and insects. 



The trout of brooks subsist largely upon insects, particularly the aquatic 

 larvfe of numei'ous species, such as caddis flies. Mayflies (Chironomus), and 

 dragonflies, and also upon insects that fall upon the water or hover the water 

 while depositing their eggs. The food of trout of larger streams, ponds, and 

 lakes, of course, consists of the particular kinds that the waters afford, and 

 these often differ materially from each other and seasonably in the same 

 water. In all waters there is a seasonal supply of insects that varies with the 

 season and locality ; but where food in the form of fishes is available the insect 

 food appears to be more or less neglected, particularly by the larger fish. 



The diet of the trout, however, varies not only with the season but with the 

 age of the fish. The seasonal variation, however, may be one of convenience, 

 but that of different stages of growth is influenced by suitability. The first 

 food of trout fry consists largely of minute crustaceans and small insect larvse, 

 such as Chironomus, black fly, etc., and that of the fingerling of larger insect 

 larvae, worms, and small insects, which diet, however, is not exclusive and is 

 controlled more or less by the habitat and environment. 



COMMERCIAL IMPORTANCE. 



While not to be compared in this respect with most of the fishes 

 prominent in our market fisheries, there has been developed in re- 

 cent years an important and apparently growing industry in con- 

 nection with the brook trout. The comparative ease with which it 

 may be brought under domestication, the constantly increasing de- 

 mand in this country and elsewhere for the eyed eggs and finger- 

 lings for the stocking of public and private waters, and the ready 

 sale in many sections of the country for the adult fish at high 

 prices as a table delicacy has induced a number of fish-culturists 

 to undertake their artificial propagation on a commercial basis in 

 New England, Pennsylvania, New York, and in many sections of 

 the Western States. As the brook trout usually will spawn during 



