PREFACE. 



This volume of the New York Aquarium Nature Series has 

 been prepared with a view to giving concise information as to 

 the best methods of caring for small aquaria in the home. It 

 deals especially with the balanced aquarium, since this is un- 

 doubtedly the best type of aquarium for home use. Not only 

 does it approach more nearly to the natural conditions of life in 

 small ponds, and therefore is of more value as an object for 

 study, but it is easier to care for and is independent of all con- 

 nections with water pipes and machinery. It is, of course, quite 

 possible to have a circulation of water even in small aquarium 

 tanks, but this involves connections with water pipes or com- 

 plicated machinery with greater expense. The balanced aquari- 

 um requires no costly or complicated apparatus ; — merely a 

 tank with a few of the simplest implements, which, for the most 

 part, can just as well be made at home. Such aquaria yield a 

 maximum of interest with a minimum of care and expense and 

 are, therefore, the most useful of all small aquaria. 



Requests for information as to the care of such aquaria 

 have been received so frequently at the New York Aquarium, 

 that in March, 1912, the writer prepared for publication a bul- 

 letin entitled "The Balanced Aquarium" (Bulletin No. 50, New 

 York Zoological Society, March, 1912). An edition of 1000 

 copies was placed on sale at the Aquarium, but this was 

 exhausted in a few months. The demands for information have 

 not ceased, however, and to meet this need the former bulletin 

 has been rewritten and much extended and is again offered to 

 the public under the present title. 



No attempt has been made to discuss the various animals 

 and plants of the Aquarium, since this w^ould necessitate a very 

 much larger volume. It is the writer's intention merely to 

 explain the conditions of life in the balanced aquarium and to 

 indicate how those conditions can best be maintained in the sim- 

 plest fashion. 



The work is not intended for those who are already experi- 

 enced aquarists, but for the use of beginners in the subject who 

 wish to become expert in this delectable occupation. 



