AQUARIUM MANAGEMENT 11 



about a quarter inch, where it will "set" in a few minutes. Score into 

 small squares as soon as firm enough to take a crease, which is about 

 three minutes. When drjr it is easily removed and broken on the 

 scored lines. 



Plant Life and the Balanced Aquarium. Fishes, as we have 

 stated, live by absorbing oxygen, and they give off carbon dioxide 

 as the waste product of their chemical lives. Plants, under the influ- 

 ence of daylight, do the exact opposite, so that what is poison to one 

 is life to the other. Therefore if an aquarium has its full quota of 

 fishes it is very desirable to have plants to increase the supply of 

 oxygen, because at times the absorption at the surface is insufficient. 

 If, however, there be a great abundance of water surface, plants 

 become more ornamental than necessary. As this is seldom the case, 

 it may be stated as a general fact that growing plants perform a 

 valuable service in the acjuarium and will often turn the scale from 

 failure to success. While the mutually beneficial interchange between 

 plants and fishes is not maintained with uniform exactness, the term 

 "balanced aquarium" expresses the condition rather happily. In this 

 connection it is an interesting fact that plants thrive much better in 

 an aquarium where there are fishes than where there are none. 



Light. Plants rec^uire daylight in order to do their work. With- 

 out it they are worse than useless. Select for the aquarium a place 

 close to a window with a good, strong light, preferably one where it 

 will get about two hours of direct sun a day. In hot weather one 

 should be careful not to overheat a small aquarium in the sun. 



Some enthusiasts, in order to provide against the short, dark day 

 and the low barometer, equip their aquaria with compressed air pipes, 

 so as to liberate small bubbles at the bottom and thus be assured of 

 a plentiful supply of oxygen at all times. This keeps the sediment 

 stirred up and is a refinement of doubtful value. The scheme was 

 quite a fad at one time, but has largely died out. Air pumps, operated 

 either by water power or electricity, may be had. The latter are 

 rather expensive. 



Aquarium Plants. Different plants have varying powers of pro- 

 ducing oxygen. It is therefore well to bear this in mind when making 

 a selection for planting. Purely ornamental plants are desirable only 

 after a fully sufficient quantity of the oxygen-producers have been 

 provided. In the order of their oxygenating powers we would name, 

 Anacharis, Vallisneria, Sagittaria, Nitella, Herpestis, Fontinalis, 

 Potamogeton, Ludwigia and others which will be more fully described 

 later. 



