850 BULLETIN OF THE BUREAU OF FISHERIES. 



at its close, October 19, when there were but 5 fish, 166 square inches, equiva- 

 lent to 105 square inches for the entire period; and the other lot (1939N') had 

 in like manner the equivalent of 20.4 square inches space for each fish during the 

 entire period; while the two control lots (19392' and 19392^) had during the 

 same period a mean of only 1.7 square inches oer fish for the first and 1.9 square 

 inches per fish for the other. 



It is interesting to note, further, that while the lots of fish that were kept 

 on the Spratt's food regimen until the October count had a generous allowance 

 of space, they failed utterly to receive benefit from it in the matter of growth. 

 Thus the lot of fish fed on the aquarium cereal ( 1 939N) , although enj oying through 

 the rescue period a mean of 12 square inches of space per fish against 9 square 

 inches per fish accorded to the liver-fed rescued lot, attained a weight less than 

 one-fifth that of the liver-fed fish ; and in the case of the fish fed on fibrine the 

 disparity was still greater, the fibrine fish attaining less than one-sixth the weight 

 of the rescued fish, although the space accorded them per fish was almost exactly 

 the same for the two. 



The conclusion to be drawn from the results of these experiments can not 

 be otherwise than this: That all of the commercial foods tried, the "fish food, " 

 the "fibrine fish food, " and the "aquarium fish food," are entirely unfit for food 

 for young salmonoid fishes. Their value for other kinds of fish is not considered 

 here. 



FRESH FISH AND RYE MEAL. 



Considerable quantities of fresh fish have been used from time to time at 

 the Craig Brook station, both as material for the growth of fly larvse and as 

 direct food. In a few instances there have been made exact observations and 

 records, which furnish limited data for demonstrations of their value. In 1907 

 such data were preserved of a brief trial of the use of fresh fish and r\'e meal. 

 The subjects of these experiments were 18 lots of brook trout, all from the same 

 original stock, all treated alike in respect to quarters, water, and attendance, 

 except that 6 of the lots contained originally half as many fish as the others and 

 were quartered in troughs half as large. All were fed on chopped hogs' liver 

 until September 5. At that date began the experimental feeding, which con- 

 tinued to October 9 to 12, when the survivors in all these lots were counted and 

 weighed. During this period 6 of these lots were fed on chopped fresh herring, 

 5 others on herring for ten days and then on a mixture of herring and rye 

 meal, and 7 others, as control lots, on liver until August i, after which hogs' 

 hearts and lights were added to their fare. Though the period of this experi- 

 ment was very short, the results seem to indicate that the continuous nourish- 

 ment with hogs' plucks was the most favorable, that fresh herring came next, 

 and that rye meal stood at the foot of the list. The 7 lots of fish fed on the 

 plucks alone, originally consisting of 1,000 fish each, or 7,000 in all, and num- 



