Three-spined Stickleback 337 



nearly so elaborate. This species feeds mostly on small 



crustaceans. 



Economic Importance: None. The Four-spined Stickleback 



is a hardy though pugnacious species easily kept in the 



salt- or brackish-water home aquarium. 



Three-spined Stickleback 

 Gasterosteus aculeatus Linnaeus 



Color: Dark green above, sometimes blue; back and upper 

 sides have faint dark bars. In breeding season red on sides. 

 Distribution: Occurs in salt and fresh waters along the 

 coasts in the northern hemisphere. In the western Atlantic 

 it is found from Labrador to Virginia. 

 Size: Reaches a length of 4 inches. 



General Information: This is a very variable species dif- 

 fering in appearance according to locality. The number of 

 bony plates on the sides varies, and sometimes no plates 

 are present. The dorsal spines may be short or long, and a 

 keel may or may not be present on the caudal peduncle. 



The Three-spined Stickleback is mostly a shore fish liv- 

 ing in the protected waters of coastal bays and estuaries, 

 but it has been taken on the surface offshore floating among 

 seaweed. It enters creeks and streams in spring to spawn. 

 The male builds a barrel-shaped nest of bits of vegetation 

 which are cemented together with sticky threads secreted 

 from his kidneys. The nest is weighted down with pebbles. 

 The male lures one or more females into the nest, where 

 each lays from 100 to 150 eggs. After laying her eggs the 

 female is driven away. The nest is guarded by the male 

 for 6-10 days, after which time the eggs hatch. The nest 

 is then destroyed, but the male continues to guard the 

 young until they are able to fend for themselves. The food 



