152 FISH CULTURE 



These will invariably attract some of the fry 

 and so distribute the groups more evenly 

 throughout the troughs, thus preventing what 

 might otherwise result in smothering. While 

 the sac remains, the fry wiU take no food, ex- 

 cept that which is furnished by the contents of 

 the sac. This is absorbed. 



The period of absorption depends largely 

 upon the temperature of the water. In most 

 spring water the period is from 35 to 45 days. 

 In creek waters it is from 60 to 120 days. The 

 lower the temperature the longer the time re- 

 quired for the absorption. Under favourable 

 conditions the growth of fry during this period 

 is very rapid. After the sac is partially ab- 

 sorbed the huddling is less persistent, and as 

 the days pass there is an increasing inclination 

 on the part of the fry to scatter. Just before 

 the sac has entirely disappeared the little fish 

 begin to rise towards the surface and scatter 

 freely over the bottom of the troughs ; and when 

 the absorption of the sac is complete the little 

 fish start to take food which is prepared for 

 them. 



The care of the fry during the absorption of 



