CuHapTerR XVII. 
CARE OF FISH IN STORES. 
When fish are kept in tanks as merchandise by dealers, the loca- 
tion of such reteptacle should be well lighted, airy, and not per- 
mitted to freeze. As was stated in another chapter, it is the oxygen 
contained in the water that the fish breathes, and it is therefore nec- 
essary to consider what means can be employed to keep up a contin- 
uous supply of it. One way, the most in use, although the worst for 
the retail customers, is to keep a stream of water constantly flowing 
through the tank. Now, thisiswrong. Goldfish are intended to live 
in standing water, and should not be made accustomed to the con- 
trary, as the reversing again of the character of the water often 
proves fatal to them. 
The proper way to keep fish is in pure standing water, to which 
the necessary oxygen is supplied by the action of aquatic plants, 
these every dealer in fancy fish is compelled to keep on hand, if he 
understands the principles upon which the aquarium is managed, and 
if he wants to make the handling of fish a financial success. 
Aquatic plants, when in a healthy condition, exposed to the light, 
consume the carbon in the carbonic acid gas which is produced by 
the fish as refuse matter, and give off the oxygen, which in turn is 
appropriated by the fish. This answers the question as to how many 
fish can be kept in a certain tank, for it is easy to understand that a 
locality favorable for the growth of plants will produce the greatest 
amount of oxygen in the water. Large fish consume more oxygen 
than small ones, so the proportion of fish to the tank must nat be 
greater than the supply of oxygen the tank can produce. Besides all 
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