Fishes. 4409 



Observations on the Nidification of Gasterosteus aculeatus and Gas- 

 terosteus spinachia. By Albany Hancock.* 



It is only within the last few years that naturalists have clearly de- 

 termined that some species of fish make nests for the reception of 

 their spawn, though Aristotle was actually acquainted with the fact 

 about twenty-two centuries ago. 



Five or six kinds are now ascertained to nidify ; and of these, two 

 belong to the genus Gasterosteus ; one, G. aculeatus, the three-spined 

 stickleback, — the other, G. spinachia, the fifteen-spined stickleback. 

 The former is a well-known, active, and pugnacious little fish, inha- 

 biting almost every pool and rivulet in the kingdom ; the latter is 

 much rarer, and is a denizen of the sea. 



Mr. Jonathan Couch states, in his interesting work entitled l Illus- 

 trations of Instinct,' that the first detailed notice of the nest-building 

 of the three-spined stickleback occurs in a little magazine * The 

 Youth's Instructor,' for the year 1834. This notice is from the pen of 

 Mr. T. Crookenden, a gentleman unknown as a naturalist, but who 

 has given a very faithful account, so far as it goes, of the nidification 

 of this species. It contains all that is at present known on the sub- 

 ject, and its accuracy can be verified by any one who will take the 

 trouble to look into almost any pool of water during the summer 

 months, — the breeding-season of the stickleback. At this time these 

 fish will be observed near to the margins, busily engaged in building 

 and guarding their nests ; and shoals of the fry may be seen, in dif- 

 ferent stages of development, swimming about in all directions. But 

 if we wish to study, to advantage, the nidification of this species, a 

 few specimens should be placed in confinement about May or June, 

 and then all their movements can be narrowly watched and accurately 

 observed. Care must be taken, however, that they be left unmolested, 

 and that their new abode resemble, as much as possible, their usual 

 haunts. I have lately had an opportunity of noticing the habits of 

 this fish, during the breeding-season, under the above favourable con- 

 ditions. 



We have, for some time past, kept a glass trough filled with aquatic 

 plants and animals : the bottom of this vessel is covered with mud, 

 and the rock-work, piled up in the centre, is overgrown with a delicate 



* Extracted from the • Transactions of the Tyneside Naturalists' Field Club,' 

 vol. ii. p. 311. 



