1 68 The Life Story of the Fish 



spring will furnish such excellent food for the little bass that 

 the latter will grow prodigiously. The bass-raising pond 

 bears about the same relation to the trout hatchery that a 

 cattle ranch, where the animals breed on the range and forage 

 for their own food, bears to a chicken farm, where the eggs 

 are hatched in incubators and the chicks are fed by hand. 



The time between fertilization of the egg and its hatching 

 varies in different species. In the brook trout it may take as 

 long as four to five months j in the muskellunge the time 

 varies from six to twenty days; in the black bass twelve days 

 is the upper limit, and in the striped bass two days suffices 

 at normal temperatures. In general, large eggs require more 

 time than small eggs. And it may be taken as axiomatic that 

 in any species the warmer the water, within the supportable 

 limits, the more quickly the eggs will hatch. 



The size of the young when they emerge from the ^g^ 

 varies with its size, for it must be remembered that the fry 

 have to be small enough to remain curled up inside until 

 they hatch. Most of the better-known marine fishes have 

 floating eggs of very small diameter — one-twenty-fifth of an 

 inch and under — whereas the eggs of almost all the fresh- 

 water fish sink, and are larger, reaching one-quarter inch and 

 more in the salmon. From this it can be seen that the larger 

 fish often have the smaller eggs, and that fish may be smaller 

 as fry than the contemporary young of other species which 

 they greatly surpass as adults. Trout fry are half an inch 

 long or over, but little swordfish, whose mother may have 

 weighed hundreds of times as much as the trout's, are only 

 one-quarter of an inch long. 



The young of most fish are at this stage by no means 

 perfect. They have comparatively huge eyes. They have 

 transparent bodies through which the beating of the heart 

 can be plainly seen. Their fins are rudimentary, and often 

 attached to each other by the "fin-fold" which later dis- 



