THE CARE OF HOME AQUARIA 21 



often purchased by the inexperienced because of their cheapness, 

 but they give the specimens a very badly distorted appearance, 

 and, what is much worse, the constricted top affords but small 

 surface area for exchange of gases with the air. Furthermore 

 the constriction of the top makes it almost impossible to clean 

 the jar properly without emptying it, and this naturally disturbs 

 the balance. The fact that a goldfish will live in a small globe, 

 with or without a small floating branch of a water plant, is no 

 excuse for keeping it in any but the most comfortable surround- 

 ings. Fishes in such globes — and how often we see them ! — are 

 compelled to go often to the surface and suck in bubbles of air to 

 obtain enough oxygen to avoid asphyxiation. The slight addi- 

 tional cost in securing the proper sort of a tank will be repaid 

 many times in the satisfaction with which it may be managed. 



To prevent the fish from jumping out of the tank a cover of 

 wire screen may be provided. As a rule there is little danger of 

 this unless the tank is filled close to the top, but some kinds of 

 active fishes are much given to leaping out of the water. 



TEMPERATURE. 



For native animals in general the degree of temperature is 

 of comparatively small importance, provided that the water is 

 not allowed to get too warm, as it will tend to do in summer if 

 the direct rays of the sun are permitted to reach it for any 

 length of time. Native fishes, as well as goldfishes and carp, will 

 endure the colder temperatures so long as the water is not al- 

 lowed to freeze, though the nearer the freezing point it ap- 

 proaches, the more sluggish become their movements and the 

 less food they will consume. The most satisfactory temperature 

 is perhaps between the degrees of 50 and 70 Fahrenheit. It 

 should be prevented from rising higher than 80 degrees or from 

 falling below 40, though there is much less danger from the 

 lower temperatures than from the higher. Some exotic fishes 

 from the tropics require a warm temperature and die when the 

 water falls below 60. Young turtles and alligators become tor- 

 pid and refuse to eat if the temperature goes down much below 

 70 and should always be kept at a hot-house temperature to 

 make the best growth. 



It is very important for all animals that the temperature 

 should not vary suddenly, since in their natural environment 

 they are not subjected to such rapid changes and hence are not 

 adapted to them. Fishes, especially the long-tailed varieties of 



