THE NEW ART OF BREEDING FISH. 65' 



CHAPTER FOUR. 



NURTURE OF THE YOUNG FISH. 



After being hatched, the youug fish observe a rigo- 

 rous diet, the term of which, varying with different 

 species, ceases with all when the umbilical bladder 

 disappears (jpl. 2, fig. 10). They feel no hunger 

 until after the nutritive elements contained in this 

 bladder have been absorbed, and while it remains 

 they refuse absolutely all other nourishment. My 

 observations, on this subject, repeatedly made with 

 different species, but principally with trout and sal- 

 mon, agree in every point with those made by Jacobi. 

 Like him, I have noted that trout do not begin to 

 eat, till towards the end of the fourth week, and that 

 salmon do not require food till six weeks after birth. 

 The knowledge of this fact is not without import- 

 ance for practical purposes, since it fixes exactly the 

 time when the feeding of the young fish should com- 

 mence. To furnish them with food before the ab- 

 sorption of the umbilical bladder, for example, on 

 the fifth or sixth day, as Mr. Haxo,* after the method 

 of the two fishermen of Bresse, recommends for trout, 

 would be censurable were it not utterly useless, for 

 two reasons : first, young trout for the first month 



* Fecondation artificielle et eclosion des ceufs de poianon. Epinal, 

 1852, p. 56. 



