FRESH-WATER AQUARIA. 23 



Fish, as has been mentioned, are nsnally not very desirable tenants, 

 as they will not join the union and become members of a " happy 

 family." The species best suited for confinement are the Roach and 

 Prussian Carp. These may be transferred from their native waters 

 direct, but the Perch, Pike, and Minnow, which also do well, should 

 first be placed in a vessel where the water is changed, but at gradually 

 increasing intervals, and in about a week or ten days they may be 

 placed in their future permanent home. Gold and Silver Fish, as is 

 well known, thrive well in a small tank, so does the common Stickle- 

 back, or Jack Bannel. This latter is one of the most interesting fish 

 we have, as it builds a nest for its young, and in the spring-time the 

 male is ver\' gorgeous in his rainbow hues. The spawn and fry of fish 

 can be kept, and are well worthy of examination with the microscope, 

 being especially instructive as examples of embryonic development 

 of vertebrates. It must be borne in mind that many creatures 

 feed on the fry, their own parents included. Beetles may be placed 

 in an aquarium in almost any numbers, but they will soon be reduced 

 to a very small one, as they are exceedingly voracious, pugnacious, and 

 regular cannibals. 



Manv other animals besides the few indicated may be kept in an 

 aquarium, but overcrowding will cause great mortality. If convenient, 

 it is well to have several large tanks, so that those animals which will 

 not keep the peace with their fellow-lodgers may be separated. It is 

 also a good plan where obje:;ts for the microscope are specially wished 

 to be always at hand to have one tank very stagnant, i.e., where the 

 conferva is encouraged to grow vigorously and never cleaned out ; but 

 if the hints given above are followed, a great number of species may 

 be kept and will tlourish in a single tank. 



