848 



ZOOLOGICAL SOCIETY BULLETIN. 



Here are shown ulv; 



BALANCED SALT-WATER AQUARIUM. 



and red seaweed, sea-anemones, ascidians, shrimps and snails 



times make too good use of their large pincers. 

 They should be provided with some sort of a 

 retreat in the form of rockwork or stones under 

 which they can hide part of the time on bright 

 days, as they are more or less nocturnal in habit, 

 some species will climb readily among the water 

 weeds. They are naturally scavengers and will 

 eat almost anything, but prefer a meat diet. 



There are numerous aquatic insects which can 

 readily be kept in the small aquarium and which 

 offer a very attractive field for study. Of those 

 available in the adult stage may be mentioned 

 the hard-shelled water beetles {Dytisms, H i/clro- 

 philits) and the whirling beetle. The water- 

 bugs such as the oarsman and the electric-light 

 bug (Belostoma) are among 

 the commoner and larger of 

 the true bugs. The larvae 

 of the dragon-flies, caddis- 

 flies and the dobson or hel- 

 gramite are even more inter- 

 esting and may be kept un- 

 til they emerge in the adult 

 winged condition. These 

 forms are chiefly carnivor- 

 ous, and if kept together the 

 smaller may disappear into 

 the rapacious stomachs of 

 the larger. The dragon-fly 

 larvae are even cannibalistic 

 and unless provided with 

 enough food the larger may 

 devour the smaller, even of 

 the same species. Any of 

 the above forms may b e 

 readilv collected with the 



aid of a small dip-net. While 

 their study has been chiefly 

 confined to the entomologist, 

 they will amply repay the 

 labors of the aquarist. 



FEEDING. 



Ill the selection of food, 

 one must naturally be gov- 

 erned by the needs of his 

 animals — some species are 

 partly or entirely herbivor- 

 ous while others are carniv- 

 orous. Practically all of our 

 native fishes are carnivorous 

 and thrive best upon a meat 

 diet of some sort, while the 

 goldfishes and carp are 

 largely vegetarian in their 

 diet. Prepared fish foods 

 may be obtained from a 

 dealer in aquarium supplies, 

 and he may be consulted as to that best adapted 

 to a particular species of fish. In the case of 

 carnivorous fishes, the prepared dry food may be 

 supplemented occasionally by the addition of 

 mealworms or of earthworms cut into small 

 pieces according to the size of the fish. Special 

 care should be taken, however, that such animal 

 food is removed if not eaten as it decays much 

 more readily than vegetable matter and so causes 

 greater danger of pollution. 



To prevent the dry prepared food from be- 

 coming scattered over the surface of the aquar- 

 ium, it is advisable to make use of a floating 

 glass ring which can be secured from a dealer. 

 This not only gives the surface of the aquarium 



COMMON ROACH IN A BALANCED AQUARIUM. 

 A very graceful and attractive species. 



