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 21% 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 /%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. 
Fic. 100. Spearmoutu (Life size) 
The body is thicker and the mandibles are shorter. From the aquarist’s 
standpoint both these larve could be classed as one. The Spearmouth is 
the larva of the large Water Scavenger Beetle (Hydrophilus). 
Dragon-Fly Larvz. 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 
Fics. 101 anp 102. Nymex oF Dracon FLy anp Larva CaTCcHING YounG FIsH 
(Life size) 
mother Dragon Fly (Odonata) is an excellent flier and may deposit her 
eggs in any body of water that provides proper facilities for her needs. 
These larve 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 
