CHAPTER V. 



FISH AS NEST-BUILDERS. 



THE idea of a fish acting as a master-builder sounds, 

 perhaps, rather astonishing and unlikely, but there 

 are one or two very interesting examples to be met with 

 among both fresh-water and marine fishes. They can- 

 not be said to erect very stately or lasting structures, 

 for their building operations are confined to the con- 

 struction of nests to hold their spawn ; and once the 

 young are hatched and have made their escape, the 

 frail structure soon falls into ruin and total disinte- 

 gration. 



I will first deal with the little Stickleback, which is a 

 familiar denizen of our streams and larger ponds, and 

 a most able nest-builder. Quite early in the year the 

 male Stickleback begins to seek for what he considers 

 a favourable building site at the bottom of the pond 

 or stream which he inhabits, and should he find another 

 male already occupying the coveted site, a most des- 

 perate encounter ensues, the rivals attacking each other 

 not only with their mouths, but with the three sharp 

 erectile spines upon the back. The victor then enters 

 into possession, his vanquished opponent slinking sorrow- 

 fully away. But the victor may not be allowed to rest 

 on his laurels in undisputed enjoyment of his newly 



56 



