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HTie Economy of 

 the Freshwater Aquarium 





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Diplonchus sp., an Australian Water-bug, Carrying Eggs. 

 Photographs by H. M. Hale. A, natural size; B, enlarged '6 x / 2 diameters. 



At a meeting of the South Australian 

 Aquarium Society held on May 4, Mr. 

 A. G. Edquist delivered an interesting 

 address on "The Economy of the Fresh 

 water Aquarium." 



The lecturer dealt largely with aquatic 

 plants and the elimination of undesirable 

 elements from the aquarium. Mention 

 was made of many species or aquatic 

 plants available and the method by which 

 each is propagated was clearly described. 

 To ensure the best growth it is necessary 

 that the plants be exposed to good light, 

 but strong diffused light is preferable 



to direct sunlight. The soil in which they 

 are rooted must contain either humus or 

 a colloid such as alumina. In fact, 

 aquatic plants flourish in a soil containing 

 the same mineral content as is suited to 

 terrestrial vegetation. They must be fed 

 and if the soil does not contain enough 

 nourishment, this can be supplied by add- 

 ing weak nutrient solutions — such as of 

 superphosphate — to the water. Although 

 the roots of aquatic plants are not adap- 

 ted for the absorption of nutriment, the 

 necessary nourishing constitutents dis- 

 solved in the water are assimilated 



