324 THE AQUARIUM 



newly hatched fishes cannot escape, although they may 

 enter freely enough. 



After the plants have been selected, and before they are 

 placed in the aquarium, they should be immersed in solu- 

 tions of salt, creolin, potassium permanganate or other 

 sterilizing agents, the action of which will not destroy their 

 tissues. This will serve to destroy any harmful parasites, 

 fungus spores, etc., which might otherwise be introduced 

 into the tank. After they have been removed from the 

 sterilizer, the plants must be rinsed thoroughly in clear 

 water, to remove all traces of it from the foliage. 



The plants used should be grouped according to their 

 needs as to light, etc., and set before the tank is filled. 

 When they have been arranged, the water should be added 

 with great care, to avoid disturbing them. This may be 

 accomplished by means of a small sprinkler, or by pour- 

 ing the water in a piece of paper free from print. After 

 the completed aquarium has stood for a day or two, to 

 insure an equable temperature and proper aeration, it is 

 ready for its occupants. 



One inch of Goldfish to each gallon of water is the safest 

 proportion for the permanent tank. 



Besides fishes, certain other creatures form part of the 

 balanced aquarium. The most important of these are the 

 snails, which, besides the added interest of their presence, 

 serve a useful purpose as scavengers, and removers of the 

 ever-present algse. There are many species, all of which are 

 more or less suitable for the aquarium. Some feed largely 

 on the plants, but when these are in a healthy growing con- 

 dition the slight depredations of the snails are negligible, 

 and more than overbalanced by the services they perform. 



The most common native species are the Pond- or Mud- 

 snails (Limncea). The most abundant form is a small, 

 blackish creature, found in ponds and ditches everywhere. 



