FRESH-WATER FISHES OF SIAM, OR THAILAND 495 



possible for the fish to shoot drops of water in quick succession, to 

 propel the water in the form of a jet when the valve is kept open longer. 



The drop-propelling function would be useless if Toxotes did not 

 possess, in addition, the ability to use its eyes in the air and to gauge 

 accurately the distance, size, and suitability for food of small crea- 

 tures flying or resting near the water's edge. It is an outstanding 

 point that, for a fish, the aerial vision of Toxotes is very keen, and it 

 was always a surprise to the present author to note the readiness 

 with which insects and spiders were sighted as the fish explored the 

 vegetation on the bank of a pond or stream. 



The archerfish, with shapely, compressed body propelled by its 

 broad caudal fin, is a graceful swimmer, moving quickly without ap- 

 parent effort. It regularly swims at or just below the surface, and 

 may go a long distance in a perfectly straight line, making a wake 

 with the tip of its jaws. This wake is characteristic and enables an 

 observer to detect the presence of a fish before he has actually seen it. 

 The habit of swimming at the surface is ascribable to two circum- 

 stances: The food on which the fish chiefly subsists is obtainable 

 there, and the eyes, on which the fish largely depends, could not other- 

 wise function properly, for during most of the year the waters in 

 which Toxotes lives are very muddy or turbid and aquatic vision is 

 much restricted. 



While Toxotes prefers the live food that it shoots for itself, it regu- 

 larly eats shrimps, insect larvae, and other creatures living in the 

 water and insects that have fallen into the water. A large nest of 

 carpenter ants impaled on a stake in a pond provided food for fish 

 for several days as the ants fell into the water and were eagerly 

 devoured. Under both semidomesticated and wild conditions the 

 fish does not reject bits of raw and cooked meat, fish, crabs, and 

 prawns. Specimens that the writer kept in a pond regularly came 

 to be fed on raw chopped pork and fish. The cavity of this fish's 

 mouth is too narrow and the sides are too rigid to permit the pas- 

 sage of a large mass of food; and it is apparent that seized insects 

 and other food must first be reduced to a slender bolus between the 

 tongue and the various bands of minute teeth on the roof of the 

 mouth before swallowing is possible. 



Some of the standard modern works of reference and textbooks 

 make inadequate allusion to the exercise of the shooting power. Thus, 

 when Boulenger (1904, p. 658) stated that '■^Toxotes jaculator derives 

 its name from its habit of capturing insects flying near the surface 

 of the water by shooting drops of water at them," he overlooked 

 the much more common and characteristic habit of stalking insects 

 that are resting on plants in the water or at the water's edge. In 

 reality, insects shot on the wing represent a very small percentage 



