Fathead Minnow
What's In a Name?
Fathead minnow: refers to the enlarged head of breeding males
Pimephales (pie-meff´-al´-ezz) means "fathead" in Greek
promelas (pro-mell´-oss) literally "before black" in Greek, possibly
referring to the darkened head of the original specimen
Where Do They Live?
Fathead minnows are found in every drainage in Minnesota. It is the most common
species of minnow in the state. They live in many kinds of lakes and streams, but
are especially common in shallow, weedy lakes; bog ponds; low-gradient, turbid
(cloudy) streams; and ditches. These habitats often have no predators and low oxygen
levels. Fatheads are noted for their ability to withstand low oxygen levels.
Fatheads commonly occur with white suckers, bluntnose minnows, common shiners,
northern redbelly dace, creek chubs, and young-of-the-year black bullheads.
How Big Do They Get?
How Long Do They Live?
Fatheads only grow to about 65-70 mm (2.6-2.8 in), and males grow bigger than
females. Most of these little fish live for only 1 year. Less than 20 % of
1-year-olds live to 2 years old. On rare occasions a fathead makes it to 3 years
old.
What Do They Eat?
Fathead minnows are considered an opportunist feeder. They eat just about anything
that they come across, such as algae, protozoa (like ameba), plant matter, insects
(adults and larvae), rotifers, and copepods.
What Eats Them?
In lakes and deeper streams, fatheads are common prey for crappies, rock bass,
perch, walleyes, largemouth bass, and northern pike. They also are eaten by snapping
turtles, herons, kingfishers, and terns. Eggs of the fathead are eaten by painted
turtles and certain large leeches. Although humans do not eat fatheads, they harvest
them as bait.
How Do They Reproduce?
Spawning season for the fathead minnow starts in late May to early June when water
temperature exceeds 16° C (about 60° F). It goes into mid-August when the
water temperatures begin to cool. About 30 days before a male begins to spawn, he
develops dark coloration, breeding tubercles (which resembles little horns) on his
head, and a soft mucus-like pad on his back between his head and dorsal fin. The
male selects the nest site, which normally is under an object such as a log, rock,
stick, pop can, or whatever may be dumped at the bottom of the waterway. The bottom
of the waterway is commonly made up of gravel or sand, which easily can be moved.
The male excavates enough of the bottom to be able to fit easily under the nest
object. He then defends it aggressively from all other fatheads. Often females have
to be very persistent to gain admission to the nest. Once the female enters the nest
she turns upside down and lays her sticky eggs on the underside of the nest object.
She then leaves to either spawn with another male or go back to where she came from.
After the female leaves the nest, the male then fertilizes the eggs. The male not
only guards his incubating eggs; he fans them with his fins and massages them with
his back pad. This keep them clean and well oxygenated. Other females may add eggs
to the nest as the spawn season goes on. The male continues his care until all of
the eggs hatch. Females produce clutches of eggs (groups of eggs that become ready
for spawning at the same time). Each clutch may contain 80-370 eggs. Most females
probably spawn several clutches in a season. We do not know the actual number. The
embryos hatch in about 4-6 days.
Conservation and Management
Fathead minnows are probably the most abundant minnow in Minnesota, and so they have
no special conservation status. Fatheads are the premier bait minnow in Minnesota
and are collected from the wild by anglers and commercial bait dealers. They also
are reared in ponds for the bait industry.
"Cool Fact": The fathead minnow was used in the past as a
form of mosquito control in many Metro Area ponds, ditches, and sloughs.
from
Natural History of Minnesota Fishes
Photographs by Konrad P. Schmidt and Donald Biemborn
Text by Nicole Paulson & Jay T. Hatch in cooperation with
the Minnesota Department of Natural Resources' MinnAqua Aquatic Program