TROPICAL AQUARIUM FISHES 



159 



It is rapacious in extreme degree and is a good swimmer. A large speci- 

 men was once placed in an aquarium for observation. It so quickly 

 attacked a goldfish that the scales fell in a small shower and the fish died 

 before it could be rescued. The males may be distinguished by the ball- 

 like development on the forelegs. They are usually of such a dark 

 brown as to appear black, but are sometimes marked or bordered with 

 yellow. 



Water Scavenger Beetle {Hydro phiUdcc). We mention this beetle 

 here because of its resemblance to the large predaceous diving beetle. It 

 swims diflferently, using its legs alternately, while the diving beetle moves 

 opposite pairs together. The Scavenger Beetle is also different in that 



Fig. 105. Water Scavenger Beetle {Life sice) 



it breathes at the surface from the mouth. Instead of long antennae they 

 have palpi looking like club-shaped antennae. This beetle lives chiefly 

 on decomposing vegetal and animal matter, although taking soft living 

 plants such as Nitella. It has been claimed to be predaceous but there 

 is doubt about their attacking fishes. They have been kept in aquaria 

 with them without doing damage. On general principles, however, it is 

 best to exclude all beetles, large or small. 



Giant Water Bug (Belostomatidcc) also known as the Electric 

 Light Bug is one of our common bugs both on land and in water. Flying 

 clumsily but strongly before electric lights, or patiently awaiting a victim 

 at the bottom of a pond, the bug is one and the same. They are fiercely 



Figs. 



106 AND 107. Giant Water Bugs (5. serphus aud B. americana) The 

 Smaller a Male With Eggs on Back (Life size) 



