AQUARIA 401 



we may know that the water is not properly oxygenated, 

 and we must take out some of the animal life or put in more 

 plants, or do both. Children will be much more inter- 

 ested in the plants and animals that they have collected for 

 their aquaria themselves ; and for other reasons we should 

 use chiefly the native life of our ponds and streams. 



A large aquarium should be permanently located before 

 it is filled. The best place is near a light window where 

 the sun shines but a few hours during the day, and then 

 it must be placed so that most of the time it may be 

 shaded from direct sunlight. It is generally stated that 

 an aquarium should stand where the sun will not shine 

 directly on it, but the plants are then apt to grow weak; 

 hence it is desirable, and should be possible, to admit 

 sunlight without moving the aquarium. However, a more 

 serious difficulty in properly locating the aquarium is that 

 of too much light. A pond receives light only from 

 above, and even there the water is generally the clearest 

 and the plants freest from overgrowths of slimes in shady 

 nooks along the shore. We must study nature closely 

 and try to imitate the conditions that produce the best 

 results in the ponds of the neighborhood. The growth 

 on the glass and plants of green or brown algae, often in 

 slimy masses that fill the water, indicates too much light. 

 Shade well for a time and put in tadpoles and snails to 

 feed upon the algse. While difficult enough to make it 

 interesting, it is a valuable study, — • that of balancing the 

 life and managing the light in an aquarium so that the 

 water will remain clear and sweet ; and the knowledge 

 thus gained will be found applicable to the conditions of 

 park waters and ponds in general. 



