Fish-Hatching in the Aquarium 321 



the yolk-bag consists of infusorians, the 

 smallest of animal life, invisible to the naked 

 eye and present in large quantities in the 

 water, as long as the aquarium is well 

 stocked with aquatic plants. When the 

 fishes are between three and four weeks old, 

 small quantities of artificial fishfood passed 

 through a very fine sieve should be given. 

 The Imperial or Bartmann's fishfood may 

 be used. It is advisable to feed frequently, 

 and in very small quantities rather than 

 once in a larger amount, as particles of food 

 not consumed at once cause impurity and 

 cloudiness of the water. 



If we wish to see our efforts in the home 

 hatching successful, it is indispensable that 

 the water in the aquarium should be kept 

 at an even temperature. It should be kept 

 as nearly as possible at 20° Centigrade (i.e. 

 68° Fahrenheit), and although it may sink 

 temporarily as low as 15 (59 F.), or rise 

 as high as 30 (jj° F. ), the middle tem- 

 perature is the most favorable. Sudden and 



