REARING YOUNG SALMONOID FISHES. 225 



this purpose in summer. Pickled alewives, freshened out in water, have been found 

 to answer fairly well, when other materials are lacking, at least to give growth to 

 maggots otherwise started. Fish pomace has not thus far given satisfaction, but 

 seems worthy of further trial. 



It is commonly necessary to expose meat but a single day to obtain sufficient fly 

 spawu ; the larva? are hatched and active the next day, except in cool weather, and 

 they attain their full growth in two or three days. To separate them from the rem- 

 nants of food and other debris was at first a troublesome task. It is now effected as 

 follows: the meat bearing the fly spawn is placed on a layer of loose hay or straw in 

 a box which has a wire-cloth bottom, and which stands inside a slightly larger box 

 with a tight wooden bottom. When full grown the maggots work their way down 

 through the hay into the lower box, where they are found nearly free from dirt. When 

 young salmon or trout first begin to feed they are qnite unable to swallow full-grown 

 maggots. Small ones are obtained for them by putting a large quantity of fly spawn 

 with a small quantity of meat, the result being that the maggots soon begin to crowd 

 each other and the surplus is worked off into the lower box before attaining great size. 

 No attempt is, however, made to induce the young fish to swallow even the smallest 

 maggots until they have been fed a while on chopped liver. 



In the above methods maggots are produced and used in considerable numbers, 

 sometimes as many as a bushel in a day. Through September, 1893, although the 

 weather and some other circumstances were not very favorable, the average daily 

 production was a little over half a bushel. They are eagerly eaten by the fish, which 

 appear to thrive on them better than on dead meat. Having great tenacity of life, 

 if not snapped up immediately by the fish they remain alive for a day or two, and, 

 as they wriggle about on the bottom, are almost certain to be finally eaten ; whereas 

 the particles of dead flesh that fall to the bottom are largely neglected by the fish and 

 begin to putrefy in a few hours. In the fish troughs there are, therefore, certain gains 

 in both cleanliness and economy from the use of maggots which may be set down as 

 compensating the waste and filthiuess of the fly-house. 



As the growth of maggots can be controlled by regulation of the temperature, it 

 is possible to keep them all winter in a pit or cellar, and advantage is taken of this 

 to use them during winter as food for fish confined in deep tanks not easily cleaned. 



The offensive odors of decaying flesh may be largely overcome by covering it, on 

 putting it away in the boxes, after the visits of the flies, with pulverized earth, and it 

 is not improbable that by this or some other method the business may be made almost 

 wholly inoffensive, but in its present stage of development it is too malodorous to 

 admit of practice in any place where there are human habitations or resorts within 

 half a mile of the spot where the maggots are grown. 



As remarked above, only flesh-eating maggots have yet been tried. It would be 

 well worth while to experiment with the larva? of other species, such as the house fly, 

 the stable fly, etc. There is also a white maggot known to grow in heaps of seaweed. 

 Should the rate of growth of either of these species be found to be satisfactory they 

 might be substituted for the flesh maggots with advantage. 



Occasional use has been made of fresh fish for direct feeding. When thrown into 

 the water after chopping it breaks up into fibers to such an extent that it is not very 

 satisfactory, and I do not suppose we shall use it in the future, unless in a coarsely 



F. C. B. 1893—15 



