ZOOLOGICAL SOCIETY BULLETIN. 



847 



These can be collected with the aid of a small 

 dip net, and the study of the local species should 

 be much more common than is the case. Why 

 so many people are satisfied to keep ordinary 

 goldfishes when there are so many native fishes 

 of more lively habits and graceful form, is only 

 to be explained by the fact that they give so 

 little trouble and can be bought of a dealer 

 instead of collected at a brook. Of course one 

 can readily understand the attitude of the fish 

 fancier who makes a specialty of breeding the 

 various strains of goldfishes or of keeping rare 

 exotic forms of bizarre appearance or unusual 

 habits. 



One serious error into which the beginner is 

 likely to fall is that of overstocking. In his en- 

 thusiasm for the fishes and his love for their at- 

 tractive colors and movements, he places more 

 specimens in his tank than can be readily pro- 

 vided with oxygen. Often, when they are not 

 all affected in a short time, the result may be 

 that they are gradually enervated until the loss 

 of some of them establishes a proper balance 

 of the animal and vegetable life. Until the 

 management of the aquarium is thoroughly mas- 

 tered, the rule should be to keep well under the 

 limit of animal life. 



It is difficult to lay down any hard and fast 

 rule for this, because the number of fishes that 

 can be kept depends upon their size and kind as 

 well as upon the proportions of the tank and 

 the amount of plant life in good thrifty condi- 

 tion. It may be stated that the beginner will 

 do well to supply only a couple of fishes three 

 or four inches long to an aquarium of five or six 

 gallons of water when the plants are in good 

 condition. When he is well enough acquainted 

 with the habits and appearance of his fishes, he 

 will be able to know at once when his tanks are 

 overstocked before any losses take place. 



There are, of course, many sorts of animals 

 besides fishes that are adapted to aquarium life. 

 The tadpoles, larvae of frogs and toads, are 

 easily collected in any pond, or some of them 

 may be purchased from dealers. In addition 

 to their interesting habits they are useful scav- 

 engers, but unless they are large it will not do 

 to introduce them into the aquarium with car- 

 nivorous fishes. In early spring the eggs may 

 be collected and reared. Those of the frogs 

 are laid in gelatinous masses, those of the toad 

 in long strings. 



Of the numerous salamanders, the pale axolotl 

 and the common mud-puppy (Necturus) both of 

 which have external gills, are easily kept. The 

 most attractive of the salamanders is the com- 

 mon or spotted water newt (Diemictylus virides- 



cens). These beautiful and graceful little ani- 

 mals, although without gills, live well in the 

 aquarium, since they are able to absorb sufficient 

 oxygen through the skin, or may occasionally 

 rise to the surface and fill the sack-like lungs 

 with air. They swim readily with the limbs 

 folded against the sides, or they climb with ease 

 among the vegetation. They are carnivorous 

 and are best fed on mealworms and pieces of 

 earthworms. The eggs of the mud-puppy can 

 often be obtained in large masses in ponds in 

 early spring, and the larvae may be reared as 

 easily as those of the frog, but the eggs of the 

 newt are laid singly among water plants. 



Young turtles are interesting, but the most of 

 them are better adapted to terraria than to the 

 ordinary aquarium as they need to have some 

 way of climbing out of the water. The soft- 

 shell or freshwater leather turtle is more aquatic 

 than other species and does not need to climb 

 out, but must have loose sand in which it occa- 

 sionally buries itself. It is carnivorous and 

 feeds well on earthworms, mealworms and pieces 

 of fresh meat. 



Young alligators are frequently brought from 

 Florida, but it should be made a punishable of- 

 fense to do so, for sooner or later they die unless 

 special care is taken to provide them with heat 

 and sunlight. The New York Aquarium is the 

 recipient annually of manj' of these little fel- 

 lows, usualty in an emaciated condition because 

 they have not fed well, and many of them do not 

 recover, even under the care of an expert aquar- 

 ist. They should be considered strictly hot- 

 house pets and handled accordingly. 



The temperature of the ordinary living room 

 in winter is too low for alligators as they require 

 80° to 85° for their best development and should 

 not be allowed to drop below 75°. Below this 

 temperature they become sluggish and chilled 

 and refuse to eat. If kept warm enough they 

 will feed well on a varied meat diet consisting 

 of fish, crayfish, earthworms, frogs, etc., alive 

 or dead, or they will take fresh beef. The ma- 

 jority of the water turtles are also carnivorous 

 and may be given the above mentioned food, but 

 the diet should be studied, as the different spe- 

 cies vary somewhat in this respect. The same 

 conditions of temperature should be applied 

 here as with the alligators. 



The pond and river species of crayfishes are 

 well suited to the small aquarium. Those from 

 the mountain streams and cold springs are 

 harder to keep on account of the difficulty of 

 maintaining a sufficiently low temperature dur- 

 ing the warm months. They should not be kept 

 with fish smaller than themselves, for they some- 



