MANAGEMENT OF AQUARIUMS 243 



should be removed at once, since the decom- 

 position is likely to foul the water, and injure 

 the remaining fishes. 



Water-temperature is an important factor 

 for a successful aquarium. The common gold- 

 fish, such as are bought anywhere for from five 

 to ten cents each, are not very particular about 

 it, but some of the choicer varieties, especially 

 those of the scaleless type, must have a fairly 

 even water-temperature throughout the year, 

 and are liable to bladder-troubles when the 

 temperature falls below 60 degrees. There- 

 fore it is best that water for the aquarium 

 which is to contain goldfish be not less than 

 60 nor more than 70 degrees. For tropical 

 fishes the temperature must be maintained be- 

 tween 70 and 80 degrees. The green slime 

 that develops on the glass in bright sunlight 

 is not harmful to fish, but is an indication that 

 the water is perfectly pure. Most goldfish 

 culturists keep several tanks with so much 

 confervae in the water that the fish are almost 

 invisible, and put into them, as "hospitals" 

 fish that are a little "under the weather." A 

 good supply of snails, especially the Japanese 



