Latin name

Gasterosteus aculeatus

Other name

Gasterosteus bispinosus, gasterosteus teraculeatus, gasteracanthus cataphractus, gasterosteus cataphractus, gasterosteus biaculeatus, gasterosteus gymnurus,  gasterosteus semiarmatus, gasterosteus niger, gasterosteus trachurus,  gasterosteus leiurus,  gasterosteus semiloricatus, gasterosteus argyropomus, gasterosteus tetracanthus, gasterosteus brachycentrus, gasterosteus noveboracensis, gasterosteus obolarius, gasterosteus spinulosus, gasterosteus dimidiatus, gasterosteus loricatus, gasterosteus biarmatus, gasterosteus ponticus, gasterosteus neoboracensis, gasterosteus nemausensis, gasterosteus quadrispinosa, gasterosteus cuvieri, gasterosteus williamsoni,  gasterosteus inopinatus, gasterosteus plebeius, gasterosteus serratus, gasterosteus insculptus, gasterosteus intermedius, gasterosteus pugetti, gasterosteus neustrianus, gasterosteus argentatissimus, gasterosteus elegans, gasterosteus bailloni, gasterosteus texanus, gasterosteus algeriensis,  gasterosteus suppositus, gasterosteus atkinsii, gastrosteus hologymnus, gasterosteus hologymnus, gasterosteus santaeannae.

Identification

The Three-spined Stickleback has an elongated body that is compressed from the sides. The tail stalk is short. Rather than scales, the fish is covered with more than two to three dozen bony plates. There is a small, sharp barb in front of the caudal fin and three more in front of the dorsal fin. The dorsal and ventral barbs are closed with a special latch when in the raised position, forming a formidable weapon. The relatively large head has a slightly pointed snout. The mouth is small, and the upper jaw is shorter than the lower jaw. The eyes are relatively large. The gill filaments are long and slender. There are 17 to 25 filaments on the first arch in strictly freshwater forms and one or two more in passage forms. The lateral line has microscopic pores.

Features of fish fins

Dorsal spines (total): 2 - 4; Dorsal soft rays (total): 10 - 14; Anal spines: 1; Anal soft rays: 7 - 11.

The caudal fin has 7-10 branched rays and is shorter and similar in shape to the dorsal fin, which has 9-13 rays. The fan-shaped pectoral fins have unbranched rays. The pelvic fins are shaped like jagged, bony barbs. The broad caudal fin is slightly rounded.

Fish colouring

The coloration of fish depends on their age, physiological condition, habitat, and time of year. In winter, these fish are silvery-gray, but in summer, they become greenish and brownish with a silvery tint. Males and females do not differ in coloration except during the breeding period. During this time, the male's back turns bluish, while the lower body and head turn red, and the eyes turn bright blue. Just before laying eggs, females develop dark transverse stripes on their backs and sides, and the underside of their bodies turns pale yellow. After spawning, this coloration disappears.

Distribution

It is widespread in the circumpolar and temperate regions. It extends south to the Black Sea, southern Italy, the Iberian Peninsula, and North Africa. In East Asia, it is found north of Japan (35° N). In North America, it is found north of 30–32° N. It is also found in Greenland.

Habitat

The three-spined stickleback is a species that can live in both saltwater and freshwater. This benthopelagic, anadromous species prefers subtropical climates. They live at depths ranging from 0 to 100 meters. Adults inhabit freshwater, river estuaries, and coastal seas. They settle in shallow, vegetated areas on the bottom of bodies of water, usually on mud or sand.

Size

The maximum length of males of this species is 11.0 cm, and their total length is 5.1 cm. The average weight is 0.001 kg. The maximum reported age is eight years.

Behavior

These fish are mobile and gregarious. During the spawning season, the males become aggressive. They are anadromous, with numerous populations in brackish or clear freshwater and rarely in marine waters. In the sea, they inhabit coastal waters. In freshwater, adults prefer small streams but may inhabit a variety of habitats, including lakes and large rivers. Juveniles are associated with drifting seaweed. In July–August, juveniles move to the sea (passage populations) or to deeper, larger bodies of water (freshwater populations), forming large feeding swarms.

Food and feeding habits

They feed on worms, crustaceans, insect larvae and adults, drowned flying insects, and small fish. They also eat their own young and eggs.

Reproduction

The spawning behavior is the same for both freshwater and transient species. Just before breeding, the males become very territorial. They build nests out of plant material that is glued together with spiggin, a protein produced in the kidneys. Once the nest is ready, the male lures the female into it by performing a mating dance consisting of zigzag movements. The receptive female follows the male, who indicates the nest entrance by standing over it with his head down. She enters the nest and lays several hundred eggs. After she lays the eggs, the male drives her out. He then enters the nest to fertilize the eggs. He may woo another female to climb into the nest and lay eggs before he climbs in and fertilizes them. Females may lay eggs in several nests over several days, or the same male may tend to them. The male guards and aerates the eggs and young. The eggs hatch in seven to eight days. Anadromous forms usually die of exhaustion after spawning. Freshwater individuals can go through several cycles within one year, and sometimes within several years.

Fishing

The three-spined stickleback has no fishery value.

Relationship with a person

This species of fish, when produced on a large scale, can be used to feed poultry, fertilize fields, and produce feed meal and healing fat.