ZOOLOGICAL SOCIETY BULLETIN 



BALANCED SALT WATER AQIARH'M 



on the side of the jar nearest the light. The 

 animals are : 



Northern white eoral (colonies ranging in 

 size from 2 to (5 inches in diameter) ; 



Brown anemones (3 or 4); 



White anemones (3 or -1) ; 



Tunicates (Molgula) (3 or 4); 



Killifishes. 2 inches long (2 or 3); 



Variegated minnows, 2 in. long (2 or 3 ) : 



Prawns, 1 % inches long (2 or 3) ; 



Young eels. 3 or f inches long (1 or 2) ; 



Mud snails (Nassa obsoletd) (1 to 12); 



Oyster ( 1 ) ; 



Little-neck clam {Venus mercenaria) (1). 

 Warning has been given to the beginner by 

 some aquarists to limit his animals, one to 

 the gallon of water. It can be seen from the 

 list just given that a gallon will accommodate 

 more than one animal — even more than four — 

 but in experiments with marine aquaria too 

 much moderation cannot be urged at the start. 

 Sea-lettuce is absolutely essential for the bal- 

 anced aquarium. Other plants may be used 

 with it. as the red alga called flame weed 

 {(•rincllit americana), and dead, sun-dried liv- 

 droids such as Sertularia argentea and S. pin- 

 until, make good ornamental effects. 



Other animals that can be confined success- 

 fully in balanced aquaria are small mussels — 

 say a quarter of an inch in length, rock bar- 

 nacles, annelids (especially the tube dwellers). 



and very small crabs. Large crabs tear the 

 plants and catch the fishes, but small mud and 

 spider crabs, of one-half inch or so in diameter, 

 are not only interesting (crabs being truly 

 comical animals) but desirable, as they pick up 

 scraps from the bottom. The small hermit 

 crabs are especially good scavengers. 



It is well to place an inch or two of fine 

 pebbles, white sand, or bird gravel on the bot- 

 tom of the jar. and a few stones must be added 

 for the attachment of anemones and for the 

 crabs to hide under. Care must be taken to 

 wash the sand thoroughly. Bird gravel is \ cry 

 dirty and will ruin the aquarium if put in before 

 cleansing. 



Hermit crabs should be provided with empty 

 shells of a suitable size so that when they out- 

 grow the home they are living in and go house- 

 hunting for a larger one. the new tenement will 

 be at hand. They are pugnacious, and two will 

 fight hard for the possession of a desired shell. 



Little-neck clams and oysters, whose siphons 

 are always busy, are valuable as elarifiers. 



Snails that consume vegetation should be 

 avoided. The periwinkles do not thrive as well 

 in standing water, but no balanced aquarium is 

 complete without a few mud snails (Nassa ol>- 

 soleta). They do not harm the vegetation ap- 

 preciably, preferring animal food, and besides 

 being excellent scavengers, are always interest- 

 ing to observe as they move about with their in- 

 quisitive siphons traveling a little ahead like an 

 advance agent. 



Young specimens of starfishes may be kept. 

 They live on mollusks, however, and a supply 

 of the mud snails is necessary for them. It 

 would not be possible to keep an oyster, clam. 

 or any other mollusk alive in the jar with a 

 starfish, and at best the starfishes are not long- 

 lived in captivity. 



Probably the most attractive of all small 

 fishes is file sea horse; and the general desire 

 to own one is so great that people even inquire 

 if they could not keep one in the same jar with 

 their goldfishes ! The little creature is difficult 

 to provide for, except with running sea water 

 and salt water Gammarus — the minute shrimp 

 that infests the sea-lettuce. Some aquarists have 

 succeeded in maintaining sea horses for a num- 

 ber of months in balanced aquaria by feeding 

 them with fresh chopped prawn on the end of 

 a stick, which the little fish soon grows tame 

 enough to take. 



A New York dealer in aquaria and aqua- 

 rium supplies, who sells sea horses, tells us 

 that he feeds them on daphnia — the common 



