sand, and the nxjls nr stems ot the i(»iied plants sliould he huiied in the sand or tied t'j the pebbles 

 to keep tliem in a natni'al. niifii^hl position. 



Certain animals act as sra\ eiij.;ers, and hence ser\e a \er\' useful ])ni])ose in aijiiaria when intro- 

 (hiced in hmited numbers. Tlie best of these are tadpoles, and certain kinds of yastropods (snails) 

 tiiat will not attack the larger plants. Some of the snails consume the minute algc'e. and serve to keep 

 (low II tlie growth of these on the glass. In larger aquaria, one or two small specimens of mussels 

 ( i'liiii. .Iinuloiita, etc. ) may Jje allowed to burrow in the sandy bottom, and will add to the interest in 

 the a(juarium. 



A glass cover will be found \ery desirable for every aquarium. It should not fit tightly Init 

 should be ke])t a (piarter or half an inch abo\'e tlie frame b\' cork, wooden, or rubber buffers. 

 Covers reduce evaporation, exclude tlust and other foreign matter. ])re\ent the fish from leaping out. and 

 protect tliem fumi cats. rats, and other enemies.. Some acjuarists emjiloy covers made of wire gauze 

 or wire netting. 



The water in a balanced a(|uariuin quickly takes the temperature of the surrounding air, and hence 

 its tetnperature \'aries gieath" with the season and also from da\' to day. The goldfish mav be subjected 

 to a wide range of temperature without injury. Like other cold-blooded animals, so called, the gold- 

 fish assumes the temperature of the water in which it exists, and is able to adapt itself to 100°F. on one 

 hand and 33° F. on the other, the essential conditions being that a change of temperature shall be 

 gradual and that oxygen shall be present in the water in sufficient quantity. Moderately cool water, 

 say of SO'' to 70°F., is to be preferred to other temperatures. If the water is quite cold the fish are 

 sluggish and less attractive, and if very warm there is danger from putrefactive conditions in the 

 water and within the fish's intestines. Cold water is much the safer, as it has a much greater power 



to absorb and retain oxvgen. 



lOf) 



