FOR PLEASURE AND PROFIT. 25 



roughly responsible commercial fish-culturist, and be careful 

 to get true' strains 1 of Farioi only, until you are aquainted with 

 the characteristics of other varieties of trout and are fully per- 

 suaded as to 1 the advisability of introducing them into your 

 fishery. You are pretty safe with Fario; yen may not be 

 with the others. Most certainly Levenensis and Irideus are 

 both useful in their proper place, but wait until you have read 

 what I have to say about them before .sowing their eggs on 

 your redds.* 



The length of time occupied in the incubation of the' eggs 

 varies considerably, and is controlled principally by the tem- 

 perature of the water. It may be eighty days, and it may bs 

 more than one hundred ; but do not concern yourself about 

 this, for often enough the longer the time in incubation the 

 stronger the alevins. Do not disturb the eggs from the time 

 they are spawned until they hatch, but should they become 

 covered with sediment, which is plainly to be seen, let a 

 stronger volume of water down over them for a few houra 

 but not sufficient to wash them from their bed. See that no 

 debris accumulates to prevent an even and constant supply 

 of water flowing over the eggs, and you will run but little 

 risk from sediment. Two months after spawning a. slightly 

 greater volume of water may be permitted to flow over thi 

 eggs, and this may be increased very gradually until 

 they begin to hatch. As soon as the greater bulk of 

 eggs are hatched out, quite a: respectable current of water 

 may be sent over the alevins, and when the alevins have lost 

 their umbilical sac (all of which matters will be presently ex- 

 plained), run plenty of water over the fry as much, indeed, 

 as is possible without washing up the gravel or driving tho 

 young fish against the screen below. 



I have yet to tell you how best to supply the necessary food 

 for the young fish. In this place I need only say that the 

 screens, while being fine enough to keep predatory fish and 

 some other objectionable characters off the redds, are coarse 

 enough tot permit the fry leaving the redds at will. And this 



* See chapter on Rainbow, and Other Foreign Trout. 



