Fish Maladies 329 



often the lack or scarcity of oxygen may be 

 caused by too high a temperature of the 

 water. Continued hot weather may over- 

 heat the aquarium, temporarily stimulating 

 the breathing process of the fishes. A 

 prompt emptying of the tank and refilling 

 with fresh water of about the same temper- 

 ature as that first contained in the tank will 

 in most cases bring quick and complete re- 

 lief. 



When we call especial attention to the 

 temperature of the water used for refilling 

 the aquarium we do so, in order to pre- 

 vent another frequent malady, — the taking 

 cold of the fishes. Paradoxical as it may 

 appear, these cold-blooded animals are sub- 

 ject to colds. A sudden change in the tem- 

 perature is often caused by refilling the 

 aquarium with water of a much lower tem- 

 perature than that drawn off. The symp- 

 toms of a cold are labored movements. The 

 fishes swim with great difficulty, remain- 

 ing on or near the bottom, or resting on 



