TROPICAL FISHES AND AQUARIA 



231 



covers should be provided for all tropical aquaria. This helps keep the 

 temperature up and prevents the fish from leaping out, at which many 

 of them are extremely expert. Failure to replace covers has caused the 

 loss of many prized specimens. They will not suffocate if glass is down 

 close. 



If one is not blessed with a heated greenhouse or a room of warm, 

 even temperature, artificial heating becomes necessary. There are several 



Bad Principle 



Fig. 209 



Fig. 210 



Fig. 211 



Fig. 212 



Fig. 213 

 Types of Heating Methods 



Fig. 214 



devices which accomplish this purpose, but only a few are satisfactory. 

 In general those are to be avoided which concentrate the heat on a small 

 portion of the aquarium water. This action drives out oxygen and other 



