26 Fresh Water Aquarium 



water. The latter should he as clear and 

 pure as possible and free from odor. Drink- 

 ing- water, as it is furnished in most cities, 

 will usually answer the purpose, provided 

 that it is not too hard. Water containing 

 such mineral substances as iron, lime, sul- 

 phur, etc., is harmful, if not fatal to fishes and 

 should therefore be avoided. But even such 

 water can be considerably improved by be- 

 ing exposed in a flat vessel to the atmos- 

 phere, before being poured into the aqua- 

 rium. Where other suitable water cannot 

 be had, rain or river water can be used 

 without the slightest danger. Even with 

 the greatest of care the water in the aqua- 

 rium after a time may have a slightly musty 

 or swampy odor. This is caused by the 

 vegetation and does not indicate that a re- 

 newal of the water is necessary. 



THE FILLING AND EMPTYING OF THE 

 AQUARIUM. 



In filling the aquarium with water it is 

 important that the gravel and the plants on 



