TROPICAL AQUARIUM FISHES 



157 



flat, strong head, pale translucent brown color and a steady progress 

 through the water, coming to the surface frequently to breath a moment 

 through the rear end. Although growing to a length of lYz inches, at 

 which time it attacks larger fishes and any small aquatic animals, it is 

 the smaller sizes with which we are principally concerned. From a length 

 of 5-4 to 1 inch they are not so easily seen but are capable of doing great 

 mischief. 



Spearmouth. While not quite so common as the Water Tiger its 

 habits are similar and it grows to an even larger size, reaching 3 inches. 



Fig. 100. Spearmouth {Life sice) 



The body is thicker and the mandibles are shorter. From the aquarist's 

 standpoint both these larvae could be classed as one. The Spearmouth is 

 the larva of the large Water Scavenger Beetle (Hydrophilus). 



Dragon-Fly Larvae. Almost everyone who raises fish outdoors is 

 familiar with these unpleasant individuals. There are two reasons why 

 they are difficult to altogether avoid. When newly hatched they are very 

 small and will go through the same strainer as daphnia ; furthermore the 



Figs. 101 .and 102. Xvmph of Dr.agon Fly and Larva Catching Young Fish 

 (Life sise) 



mother Dra£;:on Fly (Odonata) is an excellent flier and may deposit her 

 eggs in any body of water that provides proper facilities for her needs. 

 These larvae live more by their cunning than by any agility as swimmers. 

 Waiting on a dirty pond-bottom or attached to sticks, aquatic grass or 

 other object they mark time until a victim comes within close reach. 

 Then they quickly pounce forward, extending a vicious, pincer-like 

 organ called the "mask," rarely missing the object of attack. The method 

 of propulsion through the water is peculiar, being brought about by a 

 series of expulsions of water from the hinder end. This enables them to 



