16 " U. S. BUREAU OF FISHERIES. 



particular set of conditions. But all must be repeated more or less 

 in another different set. To be regarded as successful, crustacean 

 culture, as any other culture, must economically produce a supply to 

 meet the requirements. 



To state that a project is feasible is one thing; to demonstrate it is 

 another. To what extent success has been attained in the culture of 

 any of the forms of crustaceans, and perhaps to some extent the pos- 

 sibilities of the culture of some forms in this country, will appear in 

 the discussion which follows, in which the subject of culture of crus- 

 taceans will be taken up in the same order in which the classes 

 were previously discussed : Entomostraca (Branchiopoda ; namely, 

 Phyllopoda and Cladocera, here treated separately; Copepoda; and 

 Ostracoda) and Malacostraca (Isopoda, Amphipoda, Mysidacea, 

 and Decapoda). 



ENTOMOSTRACA. 

 PHYLLOPODA. 



Culture or artificial use of Phyllopoda as fish food is mentioned by 

 no fish-culturist. While these crustaceans are temporarily abundant, 

 their occurrence is usually so irregular and uncertain that no de- 

 pendence could be put upon them for anything like a permanent sup- 

 ply. When available, use might be made of them as a collateral sup- 

 ply. They would thrive in small inclosures which may be employed 

 for raising Entomostraca. In fact it is quite possible that such in- 

 closures might become naturally stocked. In any event fairy shrimp 

 are only incidental possibilities of the augmentation of crustacean 

 food supply for the fishes. 



CLADOCEBA. 



While the food recommended for young fry is usually indefinitely 

 designated as Entomostraca, about every specific citation is of 

 Daphnia. Daphnia pulex is one of the most common forms and is 

 the one specifically mentioned as in use at Gremaz (Ain), France 

 (a noted fish-farming region). It has been calculated that the pos- 

 sible progeny of a single female might reach the astonishing figure 

 of 13,000,000,000. However, in considering the possible capacity of 

 the same female for fish- food production many adverse factors must 

 be taken into account. 



The most successful method of raising Daphnia and feeding young 

 trout at the Gremaz establishment, according to C. Raveret-Wattell 

 (1887), was to raise the crustaceans in the same inclosures in which 

 it was intended that young fish should feed. The " basin " was first 

 stocked with Daphnia and the stock allowed about a month in Avhich 

 to multiply. The young fish were then put into this inclosure, wdiere 

 they were said to find abundance of food. Wliile this stock of food 

 was being consumed another similar inclosure was prepared and 

 abundantly stocked with Daphnia, which also were allowed a month 

 for increase, when the fish were transferred to this inclosure, having 

 eaten about all of the food of the first place. A month later transfer 

 of the fish was made to the first inclosure, Avhich had been restocked 



