FISHES. 147 



the Sticklebacks themselves, they must be protected in some 

 way or other. Tor this purpose, therefore, the male Stickle- 

 backs are instinctively taught to build nests and to guard 

 their eggs and little ones to the utmost of their powers. 

 Indeed, so great is the strain of the building, the necessary 

 fighting, the incubation of the ova, and the nursing of the 

 fry, that the plucky httle fellows often leave ofE living at the 

 end of their labours. Under no circumstances can the Stickle- 

 back be described as a long-lived fish: he rarely attains a 

 greater age than three years — oftener it is much less, especially 

 in an aquarium. 



In a state of nature these fish are exceedingly destructive 

 to the fry of other fish. For instance, it has been recorded 

 (I believe, by Dr. Griinther) that one of these Sticklebacks, 

 while in a tank, devoured seventy-four young dace, each about 

 iin. long, in five hours. Two days afterwards the same 

 little glutton ate sixty-two more, and then seemed quite ready 

 to continue his feast. During this huge gastronomic feat this 

 Stickleback was under close observation. 



The natural food of the Stickleback is small aquatic insects, 

 water-worms, eggs and fry of fish. In captivity he may be 

 fed upon tiny portions of worm and pieces of meat. (Before 

 worms are cut up they should be killed by dashing them down 

 upon the ground or pavement. Their death then must be 

 quite painless.) Sticklebacks soon become very tame, and are 

 nearly always bold enough to charge one's finger or one's 

 penoU if placed too near the jealously- guarded nest. They 

 are intelligent and amusing little fish, but I venture to repeat 

 they should not be kept in confinement unless they can be 

 provided with an aquarium entirely to themselves. Under any 

 other circumstances they will be a source of annoyance and loss 

 to their owner, and of great discomfort and even misery to 

 their companions. 



The Stickleback has three strong and sharp spines on the 

 middle of his back in place of the usual dorsal fin. There is 

 a fin behind the spines. The body is rather long and com- 

 pressed ; it is without scales, but is more or less protected on 

 the sides by small plates. The ventral fins have one strong 



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