58 FRESH-WATER AQUARIA. 



(Pig. 42). Occasionally the sponge will get clogged, and require 

 taking out and cleansing. 



Other simple means of aerating the water of an aquarium 

 will readily suggest themselves to the reader, such as violently 

 agitating the water for a few minutes with a short, slender 

 stick — a penholder, for instance — or taking a small portion of 

 water from the aquarium and returning it again through the 

 fine rose of a water-can. 



