What's In a Name?
Brook stickleback: refers to the spines on its back and the small
streams where it lives
Culaea (kul-lay´-ah) a name created for this fish
inconstans (in-kon´-stans) means "variable" in Latin
Where Do They Live?
The brook stickleback is common throughout the state of Minnesota.
It favors areas of rivers, streams, lakes, and ponds that have cool,
unclouded (not turbid) waters with large amounts of vegetation. They
often are found living with white suckers, creek chubs, fathead minnows,
finescale dace, northern redbelly dace, and central mudminnows.
How Big Do They Get?
How Long Do They Live?
Brook sticklebacks are minnow-sized fish. They usually do not grow
much bigger than 60 mm (2.4 in). The biggest ones reach about 80 mm
(a little over 3 in). The brook stickleback is like many of the smaller
species in Minnesota in that it lives for only 1 to 2 years, occasionally
for 3 years.
What Do They Eat?
Brook Sticklebacks are mainly carnivorous ("meat eaters"),
but they also sometimes eat algae. The usual diet includes acuatic
(water) insect larvae, terrestrial (land) insects, waterfleas, worms,
snails, and sometimes fish eggs.
What Eats Them?
Despite the sharp spines on their backs, brook sticklebacks are eaten
by many other fish species. These include brook trout, largemouth
and smallmouth bass, northern pike, yellow perch, walleyes, and bowfins.
Fish-eating birds are also a big predator of this fish. They include
herons, kingfishers, mergansers, and terns.
How Do They Reproduce?
Brook sticklebacks spawn in late spring and early summer in Minnesota
(late May through June). Water temperatures must be above 10°
C (50° F) but below 20° C (68° F) for good spawning. Males
pick sites in the weeds and create their territories. There, they
use algae, sticks, other plant matter, and their own sticky secretion
to build a nest almost the size and shape of a golf ball. It has an
opening at one end and is attached to the stem of a plant. When a
female enters the male's territory, he rushes up to get her to go
into the nest. He will even push her in the direction of the nest.
Once inside of the nest the female lays her eggs and then forces her
way out the other side of the nest. The male then enters the nest
and fertilizes the eggs. Once he is done with that, he usually repairs
the nest to receive other spawning females. Sometimes a male builds
a second, larger nest and transfers the eggs to it (carrying them
in his mouth). Each female that visits the nest may lay 50 to 100
eggs. The male will guard the nest and young until he loses control
of the school of young fish.
Conservation and Management
Brook sticklebacks have no special conservation status in Minnesota.
They are probably important as natural controls for mosquitoes and
make an interesting aquarium fish.