value of different forms of crustaceans as food for young fishes, 

 but, assuming that those available are desirable, to indicate whether 

 or not, other things being equal, it would be practicable to raise 

 them in sufficient quantities to feed large numbers of young fish. 



Inasmuch as crustaceans vary greatly in size, as do the fish which 

 subsist upon them, it would first be necessary to supply to fry such 

 sizes as they can swallow, and larger sizes to the fish as they in- 

 crease in growth. While there are many kinds and sizes of crus- 

 taceans, most of which are natural fish foods, only certain very com- 

 mon forms have been utilized, although several have been recom- 

 mended. The kinds that have been indicated in any experiment 

 have usually been stated to be Daphnia and Cyclops for very young 

 fish and shrimp for older fish. Daphnia and Cyclops are, as most 

 fish-culturists know, minute crustaceans called Entomostraca. The 

 shrimp, of which the once famous "Caledonia shrimp" was one, are 

 amphipods or scuds. They are more suitable for fish which have 

 passed the Entomostraca-eating stage. 



The purpose of this paper is to make an analytical comparison 

 of the stated results of experiments in crustacean culture and feed- 

 ing of fish, based upon requirements according to present feeding 

 practices at some of the stations of the Bureau of Fisheries. The 

 particular purpose of the comparison is to prove or disprove the 

 contention that crustaceans cannot be raised economically on a suffi- 

 ciently large scale to meet the requirements in this country, granting 

 that other conditions are equal. As concerns Entomostraca, while 

 there are positive claims that it would be entirely feasible, there are no 

 very definite data for comparison. The only evidence in favor in- 

 dicates that after the fish attained a certain size they were fed on 

 finely-minced horse meat instead of Daphnia. 



In other connections it has been mentioned that after feeding on 

 Daphnia six or seven weeks the fish were provided with coarser 

 food. In this country it is customary to distribute fry at that age, 

 so the entomostracan production would need in no instance to con- 

 tinue for more than that length of time. This period in the life of the 

 fish is the most critical, and the one in which its food should be 

 most carefully considered. It is known that young trout naturally 

 feed upon Entomostraca when available and that the latter multiply 

 rapidly under favorable conditions; thus it would seem that some 

 method of raising them might easily be devised. Unfortunately in 

 this country there have been no definitely-described experiments. It 

 is hoped that experimental work along this line will receive early 

 attention. 



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