16 THE NEW ART OF BREEDING FISH. 



PRESERVATION OF THE YOUNG FISH. 



As incubation goes on and hatching time ap- 

 proaches, in order to determine when it will take 

 place and not to their injury retain the little fish too 

 long prisoners, the boxes should be frequently in- 

 spected. When incubation is finished and the little 

 fish begin to move, they must still be kept inclosed 

 from eight to fifteen days, according as their numbers 

 are small or great ; then they may be set at liberty 

 in the quietest part of the stream, care being taken 

 that the quality of the water is the same as that 

 which has flowed through the boxes, for a change to 

 water of more or less freshness or clearness will have 

 a sensible influence on their frail existence. 



A wide field for experiment is here open to any 

 who choose to enter upon it : for example, it would 

 be very interesting to ascertain the results of different 

 modes of treatment by placing similarly, either con- 

 fined in large boxes or at liberty in running brooks, 

 equal numbers of young fish, and supplying one set 

 with thickened blood and other food, and leaving the 

 other set to find such food as nature affords, to note 

 the relative increase. Experiments, too, might be 

 made with boxes having larger holes than those be- 

 fore described — ^large enough for the escape of the 

 young fish as soon after hatching as they might seek 

 their liberty ; which mode might do away with the 



