AGGREGATIONS OF HIGHER ANIMALS 



95 



time is why this is so. What are the factors involved 



that make this slightly contaminated water a better 



medium for young goldfish than a clean medium? 



We have said that the conditioning fish are fed 



EfFECT OF SELF CONTAMINATED WATER ON GROWTH OF GOLDFISH 



«0. 290 274 



I 



GROWTH 1.8 -0 2 



no. 180 142 



I 



I 



GROWTH 1.65 1.00 



MO. 210 120 



CONCErfTRATEO 



I 



I 



GROWTH 2.28 t.ia 



ma t6l 114 



II 



GROWTH 1.92 



Ha 220 217 



tl 



GROWTH 2.59 2.20 



Fig. 14. Goldfish grow more rapidly if placed in vari- 

 ous kinds of slightly contaminated (conditioned) water. 

 The numbers above the columns show the number of 

 fish tested. The longer column represents the growth in 

 conditioned water. 



for two or more hours daily and are then washed 

 off and placed in a fresh batch of water. Although 

 the fish are never fed in the water they are condi- 

 tioning, within a few hours after their transfer into it 

 from the feeding aquarium the water becomes more 

 or less cloudy with regurgitated food particles. These 

 bits of food are large enough so that the growth-assay 



