24 SALT-WATER FISHES 



soon as he removed the strainer (which had been introduced to 

 keep out enemies) and allowed the water to flow in direct, he 

 found that the larva; underwent rapid recovery. 



There is often considerable difficulty in determining the 

 exact food of any fish. This difficulty arises from three causes. 

 First, there is this habit, in many, of feeding on minute 

 copepoda and similar small organisms. Secondly, many fishes 

 have very rapid digestion, those which pass much of their life 

 swimming at high speed near the surface of the sea being most 

 remarkable in this respect, so that it is unusual to find any 

 trace of food in a newly caught herring or mackerel. Some of 

 the larger ground-dweUing fishes, on the other hand, like the 

 torpedo and angler-fish, appear to feed and digest more after 

 the fashion of pythons, devouring a large victim at a meal, 

 and then lying quiet to digest at leisure ; at least, we know 

 that bass and other fish have been recovered from their inside, 

 often, more particularly perhaps in the case of the electric 

 torpedo, having sustained such trifling injury that they are fit 

 for sale. The third reason for the difficulty of determining 

 the substance on which a fish has recently fed is the habit that 

 so many have of throwing up their last meal when hooked or 

 taken in the nets. Whether they do this in pain, in terror, 

 or in some hope of throwing over ballast when struggling for 

 their life and liberty, we can only surmise, but the habit is very 

 familiar to fishermen and anglers. Over and over again the 

 writer has known a bass or pollack throw up as many as three 

 or four tiny sand-eels when hauled into the boat, and the 

 boat's " well," into which the fish are thrown, often contains a 

 score or more of these small disgorged fishes, more or less 

 damaged by the teeth of their captors. 



While on the subject of the food of fishes, a word may 

 perhaps be said, by an easy transition, of fish as food. Leading 

 authorities differ in a remarkable degree as to what exactly 

 constitutes a " food-fish." Cunningham is perhaps nearest the 

 mark, yet he excludes the weevers and says little of the rays ; 



