16 American Fisheries Society 



them bodily and alive in food. Whether this cooking of 

 the food is further a physiological advantage perhaps 

 does not yet appear. 



Now, it has been said that cooking, and the use of fish 

 as food for trout are each to an extent preventives of 

 thyroid tumor. But some recent observations make it 

 seem certain that neither alone is sufficient for this end. 

 One is the occurrence already mentioned, of such tumors, 

 in a small percentage, in the sea bass of the Naples 

 aquarium on a raw fish diet. The other is a practice at a 

 commercial trout farm in Pennsylvania which consti- 

 tutes a departure in brook trout feeding which should be 

 of much interest to this society aside from any bearing it 

 may have on the present subject. At this hatchery the 

 fry are fed for about two months on beef liver in the 

 usual way. Then a wheat flour mush is added in small 

 and very gradually increasing quantity until by the end 

 of the next four months all the liver is eliminated. After 

 this nothing but cooked flour mush is fed and the trout 

 are so reared to adults. The trout keep in fine condition, 

 resemble wild fish in color and activity and make a sur- 

 passing table trout, but they do not grow rapidly. The 

 object of the feeding is to produce a fish resembling the 

 wild trout in edible qualities and without the flavor of 

 liver fed fish. In this success has been achieved and the 

 adults reach a high-priced market. Trout so fed are 

 used as breeders and yield a good quality of eggs which 

 hatch out with excellent results, but it is not claimed that 

 this flour feeding has any advantages from the breeding 

 standpoint. It has been adopted solely to obtain a su- 

 perior table trout, and this result is achieved at consider- 

 able sacrifice of the rate of growth. By universal experi- 

 ence it appears to be demonstrated that rapid growth 

 requires meat or fish feeding. 



From other sources, where trials have been made with 

 a purely vegetable food, opinion is for the most part 

 against the practice. Here it is necessary to direct at- 

 tention to the fact, often demonstrated in fish culture, 

 that the same methods do not work out alike in all hatch- 



