THE GOLDFISH AND I1S CULTURE, 57 
motion up and down; avoid touching the sand, as this would 
scratch the glass The aquarium will now appear as clear as 
if it contained no water at all. Now introduce the fish gently, 
one at a time, getting them gradually used to the temperature 
of the water by slowly mixing it with the water in which they 
were, then add to your collection two or more frog tadpoles 
and a few pond snails of the rams-horn type to consume the 
refuse and otherwise decaying matter that will be about. 
NUMBER OF SPECIMENS. 
The question how many fish can live in an aquarium of a 
certain size, is equal to: how much money must a person have 
to be rich? The answer is substantially the same. The shape 
of the tank and the location in which it is placed determine 
the number of fish that can comfortably live in it. Should 
the location be bad as regards light, the amount of oxygen 
generated in the tank will be small, while if the situation is 
highly favorable in every respect, the evolution of the life- 
giving gas will reach its maximum degree. 
The quantity of water required for a given number of fish 
is furthermore regulated by their size and the nature of the 
treatment they have received before they came into your pos- 
session. If, for instance, they were kept in running water, or 
were newly caught in a large pond, they will naturally require 
a much larger quantity of water than if they had already been 
accustomed to a life of captivity. Some fish need a great 
amount of oxygen, while others get along with remarkably lit- 
tle. An aquarium will stand as many fish as the plants can 
supply with oxygen. 
The only way to ascertain the ability of a tank is by be- 
ginning with a few specimens, adding from time to time until 
& 
