sible, the aquarium should be such that it will contain a rectangular volume 

 of water as high as wide and twice as long. For a permanent set-up an inch 

 or more of good garden soil should be tamped firmly into the bottom and 

 covered with an inch-deep layer of sand that has been washed in several 

 changes of water until it is free from sediment. Then a sheet of paper may 

 be laid on the sand, the water slowly added, and the paper removed. This 

 method of adding water serves to keep the sand and soil from being disturbed. 

 Filtered pond water is best, if available. City water that contains chlorine 

 should be avoided, if possible, or at least allowed to stand in the open for 

 several days before it is used. Plants may next be set out. Elodea is excellent, 

 if kept trimmed. ValUsnena, the Ribbon Grass, is also very good. Then, 

 most important of all, the planted aquarium should be allowed to stand for 

 several days before any animals are introduced. If the plants start to grow 

 and the water remains clear, all is well. If not, the water should be gently 

 siphoned off and more added. Animals should not be crowded. If too many 

 are introduced, they damage each other and the plants, and the water becomes 

 cloudy. Food not cleaned up within an hour should be removed. If the 

 aquarium is set up properly and attains a balanced condition, it should remain 

 clear and never need changing. Enough water should be added from time to 

 time to make up for that lost through evaporation. If the water becomes 

 green, it is receiving too much light, and unicellular green algae are develop- 

 ing. These algae do not harm the animal inhabitants of the aquarium, but 

 do reduce the visibility. To correct this condition the light should be reduced 

 and a small clam put in for a week or two to filter out and eat the algae. 



The terrarium is for land animals or those that spend most of their time 

 on the banks of ponds or streams. Turtles, frogs, some salamanders, lizards 

 and small snakes do well in terraria. A large, old aquarium, discarded because 

 of leaks or cracked glass, can often be utilized in this fashion. A shallow 

 dish of water is set within, and the rest of the floor covered with liverworts 

 or moss. A glass cover, slightly raised by toothpicks or matches, should be 

 used. Such a greenhouse will flourish for months with little attention except 

 that necessary for its animal occupants, although an occasional "lawn mowing" 

 with a pair of shears may be necessary. 



A combination of aquarium and terrarium is possible in a long con- 

 tainer. One end can be raised so that a "shore line" occurs in the middle of 

 the tank, and a little sphagnum or water-moss put along this edge. Cray 

 fishes, hellgrammites, turtles, most salamanders and many other creatures 

 thrive in such an environment. Small worms, snails, and Drosophih. or fruit 

 flies and other insects make acceptable food for most of these animals. Such a 

 terrarium should also be kept covered. 



For larger animals, particularly birds and mammals, various types of 

 cages are available. A caged animal should always be given plenty of room 



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