84 



ZOOLOGICAL SOCIETY BULLETIN 



BALANCED AQUARIA. 



THE CARE OF BALANCED AQUARIA 



THE laboratory of the New York Aqua- 

 rium has a fine collection of fresh and 

 salt water aquaria, of the kind known as 

 "balanced," or self-sustaining. The jars are 

 of uniform size, holding eight gallons of wa- 

 ter. Containing plant and animal life in 

 proper proportions as they do, the water in 

 them is never changed. In fact, they are 

 maintained with as little disturbance as pos- 

 sible, a little feeding and occasional cleaning 

 being all that is necessary under ordinary 

 conditions. The series as a whole presents a 

 number of interesting object-lessons in ma- 

 rine and aquatic life. 



As it is much visited by teachers and 

 classes from the schools, the collection has 

 recently been increased by the addition of 

 several jars. 



Among the forms to be seen in the salt- 

 water jars are sea anemones, barnacles, corals, 

 marine-worms, mussels, clams, hermit and 

 horseshoe crabs. The opportunities which 

 small aquaria afiford for observing the natural 

 movements of these living creatures are ex- 

 cellent. 



Through the co-operation of the Board of 

 Education the Director of the Aquarium has 

 undertaken to assist the bioloey teachers of 

 New York in maintaining small collections of 

 this kind in their class-rooms, and a compe- 

 tent aquarist has been detailed for that duty. 



the Acjuarium furnishing only the animal 

 life necessary to stock the jars. As the 

 Aquarium now has a field collector, this can 

 easily be done from the surplus material re- 

 ceived weekly. About thirty aquaria have al- 

 ready been set up in as many high schools, 

 but this has been done with the understand- 

 ing that the Aquarium be put to no expense 

 for jars or fixtures. The teachers have ex- 

 hibited so much interest in the matter that it 

 has been found desirable to prepare brief in- 

 structions regarding the establishment of such 

 collections, and the proper way of caring for 

 them. 



The following directions for the care of 

 balanced aquaria have been prepared by Mr. 

 L. B. Spencer, who is in charge of the collec- 

 tion in the laboratory of the New York 

 Aquarium : 



"Probabl}- a majority of those who keep 

 small at|uaria, with a few goldfish as inhab- 

 itants, make a practice of frecjuently chang- 

 ing a part of the water, that the fishes may 

 not die for lack of air. If the person who 

 cares for them forgets to change the water 

 or does not do so often enough the chances 

 are that some or all of the fishes may die. 

 Then again, many people take the fishes out 

 of the aquarium with the hands or a net, to 

 wash the interior, putting in fresh water and 

 then returning the fishes, and in this way the 



