1,500 pounds of fish. The mush contains little or no nutriment, but 

 the same may be said of the shells of the shrimp. So far as the 

 figures are concerned, however, the comparison is somewhat in favor 

 of the mush-liver combination. On the other hand, 4,000 yearling 

 brook trout at Spearfish were fed 372 pounds of mush and 217 

 pounds of liver, a total of 589 pounds. At Gremaz 20,000 trout 8 to 

 12 months old required 600 to 800 pounds of shrimp, which repre- 

 sents 30 to 40 pounds for every 1,000 fish, or 120 to 160 pounds for 

 4,000 fish. This throws the advantage to the crustaceans. There 

 was probably much waste in the Spearfish feeding. 



At the Springville (Utah) station 8,000 brood-stock rainbow 

 trout averaging one pound in weight, were fed in one month 744 

 pounds of mush and 496 pounds of liver, or 1,240 pounds of the 

 combination. At Gremaz it would have required 400 to 426 2/3 

 pounds to feed that many pounds of fish averaging one-half pound 

 each, which suggests an advantage for Crustacea. 



At the Wytheville (Va.) station 1,000 yearlings 8 to 12 inches 

 long were fed 12 pounds a day. At Gremaz, 1,000 fish of approxi- 

 mately the same age were fed about 7 or 8 pounds a day, which is 

 favorable to crustaceans. At Wytheville again, 1,000 fish 3 to 5 

 inches long were fed three-fourths of a pound a day. At Gremaz 

 the daily ration per 1,000 fish of about the same age was one to 2^ 

 pounds, which favors Wytheville feeding. 



There are elements of error in these computations, but they indi- 

 cate on the whole a not very great difference in the amounts fed to 

 fish of the various sizes at Gremaz and in this country. Doubtless 

 it would be practically impossible, if at all desirable, to provide an 

 exclusively crustacean diet for trout of all ages. It has been demon- 

 strated, however, that crustaceans can be cultivated in quantities; 

 local conditions and the available crustaceans would largely deter- 

 mine the extent of operations. It would seem then, that a consider- 

 able collateral supply of crustacean food would be economically pos- 

 sible and provide a much desired variation in the kinds of food. The 

 largest trout would require more food and perhaps greater variety. 

 Possibly this variety could be provided by utilizing the prawn, as 

 advocated by Worth.^ It is probable that the prawn can be raised 

 quite as easily as the shrimp or scuds (Amphipoda), if the condi- 

 tions under which they live naturally are followed in the artificial 

 ponds. It should always be borne in mind that all of these organisms, 

 from the most minute to the largest, require food and that no experi- 

 ment can be successful unless it is supplied. 



^Bull. U. S. Bureau of Fisheries, Vol. XXVIII, 1908, Pt. II, pp. 853-858. 



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