THE CARE OF HOME AQUARIA 



53 



COMMON ROACH IX A BALANCED AQUARIUM. 

 A very graceful and attractive species. 



out, producing a very rough appearance. Nothing definite is 

 known as to the cause of this disease and if it has made much 

 progress there seems to be no cure for it. In such a case it is 

 better to kill the fish at once and thus put it out of its misery. If 

 the fish is a valuable one and the disease is incipient, it may pay 

 to attempt to cure it by putting the fish on a scanty diet and giv- 

 ing it a tank by itself where it will have plenty of room and the 

 best conditions of temperature, light and oxygen. 



Chill is a frequent source of trouble and to avoid this the I 

 fishes should be kept from draughts in winter and water should 

 not be added to the tank until it has been warmed to the tem-l 

 perature of that in the aquarium. If they should happen to be-l 

 come chilled, remove the aquarium to a warm place at once and[ 

 put in some warm water raising the temperature to 80 or 8^ 

 degrees, afterward allowing it to fall gradually to the normal. 

 If prompt action is taken no loss should occur. Frequent suddei 

 changes in temperature are very deleterious and should b( 

 avoided absolutely. 



Other diseases are known to occur among fishes, but ver^ 

 few of them have been studied with any care. Perhaps the besj 

 known is the thyroid disease, or goitre, of the salmonoid fishes 

 which has been a subject of much investigation in recent yean 

 This has been proved to result from improper conditions in thl 



