244 FISH CULTURE 



and African species, will keep the glass of the 

 aquarium fairly clear of slime. 



Purity of water is naturally of first impor- 

 tance. Fortunately it is generally easy to de- 

 tect impurity. A disagreeable odor usually 

 manifests itself, and almost invariably the water 

 becomes slightly cloudy. Fish and snails com- 

 ing to the top of the water on clear sunshiny 

 days give a strong indication of foul water. 

 When it becomes necessary to change the water 

 in an aquarium, it is better not to dip it out 

 but to draw it out by means of a siphon (rubber 

 tube) ; when the tank is half empty, remove the 

 fish by means of a small net. The water 

 should also be replaced in the same manner so 

 as not to displace the sand and gravel at the 

 bottom. 



Some people like to place rockwork in an 

 aquarium. Where it can be done this is desir- 

 able both for the fish and as resting places for 

 the tadpoles, and it should project a little above 

 the surface of the water. 



Care of Goldfish. Goldfish, after the man- 

 ner of other carp, like to jump once in a while, 

 so there must be either a considerable space 



