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The first edition of this guide was completed in 1990 and published
in 1991. Since then it has been a primary source of information
on identification of North American freshwater fishes. This
second edition increases the number of species in the guide from
768 to 909, incorporates new maps and several new and revised
plates, and corrects errors. The increase in number of species is
the result of adding 114 newly recognized species native to the
U.S. and Canada, 19 marine invaders commonly found in freshwater,
and 16 newly established non-native (exotic) species. Eight
species recognized in the first edition were deleted as names were
synonymized or as exotic species thought to be established disappeared.
The ichthyofauna of the twenty-first century is not that
of the twentieth century, and a revision of this guide was badly
needed. We hope we have succeeded in making it current as well
as more user-friendly. Suggestions for improvements and notifications
of errors are welcome.—LMP and BMB
How To Use This Guide
Naturalists, anglers, and aquarists derive pleasure and knowledge
from observing and catching fishes. Ichthyologists and other scientists
study fishes to learn more about the evolution of life, the
history of our continent, and how natural resources can be better
managed. For these interests and related endeavors, accurate
identification of fishes is essential. This guide includes all fishes
in fresh waters of North America north of Mexico.
Fishes are aquatic vertebrates with fins and gills throughout
life. Currently recognized as valid are about 31,000 species, of
which 831 species (3 percent of the total) are native to fresh waters
of the United States and Canada. Another 58 species from
elsewhere in the world have been established in our area, and 20
marine species are encountered often enough in fresh water to
be included in this guide, bringing the total number of species to
Of the 537 families of fishes, 34 (6 percent) are represented by
1 or more species native to freshwater lakes and streams of the
United States and Canada, and another 11 families have marine
species that occasionally enter our rivers. Eight other families
are represented by introduced (exotic) species. Although our fish
fauna represents a fraction of the world’s total, it is Earth’s most
diverse temperate freshwater fish fauna.
All freshwater fishes known from North America north of
Mexico are included in this guide. The Peterson Field Guide to
Atlantic Coast Fishes and the Peterson Field Guide to Pacific Coast
Fishes provide additional information on marine and brackishwater
fishes likely to be encountered in fresh water.
Most names of fishes used in this guide are those in Common
and Scientific Names of Fishes from the United States, Canada,
and Mexico, published in 2004 by a joint committee of the American
Fisheries Society and the American Society of Ichthyologists
and Herpetologists. In a few instances in which the committee
changed a common name, we chose to keep the name used in the
first edition of this field guide.
Scientific names of species consist of two Latinized and italicized
words, e.g., Lepomis punctatus. The first is the genus, which
begins with a capital letter. The second is the “specific epithet”
and is not capitalized. A subspecies has a third descriptor, e.g., Lepomis
punctatus miniatus. Genera are grouped into families (with
names that end in idae), families into orders (ending in iformes),
and orders into classes.
Color plates were painted from live fishes or, more often, from
color photographs of live or freshly preserved fishes. Black-andwhite
plates depict fishes that lack bright colors or show little
variation in color among closely related species. Fishes are not
drawn to scale, but much larger species usually are shown larger
than smaller species. The 57 plates (42 in color, 15 in black and
white) show 824 individuals representing 677 species. Additional
species are illustrated in text figures.
Although ichthyologists use the metric system, guide users remain
familiar with inches, feet, and pounds. Measurements are given
in both systems. A short rule comparing metric and U.S. units
appears below and on the back cover. The maximum total length
known (tip of snout, lip, or chin—whichever is farthest forward—
to end of longer caudal fin lobe) is given for each species. For
small fishes, this number is given in quarter-inches and tenths
of centimeters, for intermediate fishes in inches and centimeters,
and for large fishes in feet and meters.
If the maximum length recorded was given originally in centimeters,
it was converted to inches; if in inches, it was converted
to centimeters. Rounding from centimeters to quarter-inches can
give various results; for example, 7.4 through 7.9 cm are all given
as equivalent to 3 in.
Family accounts provide information on distinguishing characters
(often anatomical) and distribution. Numbers in parentheses following
family names are numbers of native species in the United
States and Canada; if introduced species are in our area, number
of natives is followed by number of exotics.
Generic accounts are given for large genera and for small genera
in which all species share characters useful in identification.
If a character is described in a family or generic account, it usually
is not repeated in a species account.
Species accounts begin with common and scientific names. In
the upper right-hand corner of each account is the number of the
plate or figure where the species is illustrated, or “Not shown” if
not illustrated. A species is not illustrated if it is similar to another
Most species accounts contain the following four sections. A
similar Species section is omitted if a species is easily identified,
and a Remarks section is added if the species has subspecies or
other noteworthy characters.
Identification: This section describes the most useful characters
for identification. Usually these are color descriptions such
as “black stripe along body,” shape descriptions such as “dorsal
fin origin behind pelvic fin origin,” and unusual features such as
“barbel at corner of mouth.” The most prominent field characters
are italicized and usually appear early in the account. Accurate
field identifications sometimes require consideration of locality
and habitat. Large specimens, especially colorful males, are easiest
to identify. Positive identification of small or single individuals
may require close examination; for that reason, we give some
characters useful in identification of preserved fishes (numbers of
scales, fin rays, and pharyngeal teeth, etc.).
A color description is included unless a species is noted to be
similar or nearly identical to another species. Unless stated otherwise,
the description is of an adult fish, and the fish is white
below (breast and belly) and has clear fins, conditions that pertain
in most species. In many fishes, females retain colors similar
to those of young, but males become notably brighter or darker
with age. During the spawning season, males often become
much brighter in color than at any other time. When known to
differ, both “average” and “breeding male” descriptions are given.
In some fishes (e.g., darters), large males retain bright colors
through much of the year; in others (e.g., most minnows), bright
colors are present only during the spawning season.
Counts provided are those considered to be most important for
identification and are total ranges unless they are preceded by
“usually” or identified as modes (i.e., number[s] occurring most
frequently). Counts of bilateral characters are given for one side
only, e.g., six branchiostegal rays means six on each side. Pectoral
and pelvic fins come one to a side and are referred to collectively
(i.e., all four of them) as paired fins. We often discuss these fins
and other paired structures (e.g., eyes) in the singular (e.g., pectoral
fin, eye) to simplify comparisons between species. Dorsal,
caudal, and anal fins are referred to collectively as median fins.
Range: A description of each species’ geographic distribution is
followed by a comment on abundance (e.g., “Rare”). All species
vary in abundance with locality, and the statement on abundance
is meant to apply over the species’ range or, if introduced, over
its range in the U.S. and Canada. The statement is not a relative
comparison among species. For example, the Fountain Darter,
Etheostoma fonticola, is common in its area but is considered
an endangered species because it occurs in only one small area.
Abundant means a species is almost certain to be found in its
preferred habitat within its range (see “How to Observe Fishes”);
common indicates a species is likely to be found; fairly common,
may be found; uncommon, unlikely to be found; rare, very unlikely
to be found. Species and subspecies described as threatened
or endangered are those appearing on official lists of Canada
(Species at Risk Act – SARA) and the United States (USFWS) as
of 1 July 2010. Many species also are legally protected by states or
Habitat: Fishes vary widely in their restriction to particular
habitats. Some are extremely limited (e.g., to springs); others can
occupy habitats as different from one another as gravel riffles and
swamps. For a stream-inhabiting species, a habitat description
includes a statement on the size of stream the species generally
occupies. Terms used are streams (any body of running water),
headwater (a stream less than 3 ft. [1 m] wide during average condition),
creek (3–15 ft. [1–5 m]), small river (15–80 ft. [5–25 m]),
medium river (80–165 ft. [25–50 m]), and large river (more than 165
ft. [50 m]). A basin is a major drainage unit (e.g., Arctic, Hudson
Bay, Great Lakes-St. Lawrence, Atlantic, Gulf, Pacific, Mississippi
R., Ohio R., and Missouri R. basins) or an independent endorheic
drainage unit (e.g., Bonneville basin). Component drainages may
be referred to collectively as, for example, Atlantic drainages. A
drainage is an interconnected group of streams entering an ocean
or main river of a basin (e.g., Wabash R. drainage of the Ohio R.
basin). A system is a subdivision of a drainage (e.g., Embarras R.
system of the Wabash R. drainage).
For convenience, we make a distinction between Atlantic and
Gulf slope drainages even though the Gulf of Mexico is part of
the Atlantic Ocean. Atlantic Slope drainages are those entering
the Atlantic Ocean from the Arctic Ocean to the southern tip
of Florida. Gulf Slope drainages are those entering the Gulf of
Composition of the stream or lake bottom (substrate) is of
major importance in distributions of fishes, and habitat descriptions
usually include statements on the type(s) of bottom material
most often associated with the species. Mud refers to a soft
bottom (clay or silt); rock refers to a hard bottom (gravel, rubble,
boulders, or mixtures thereof). More precise terms, in increasing
order of particle size, are clay, silt, sand, gravel, rubble, boulders,
Similar species: Comparisons are made with species that appear
most similar. These species usually, but not always, are closely
related forms. When there are many similar species, we compare
those closest to the range of the species being identified.
Range maps are provided for all extant (and some extinct) freshwater
fishes native to North America north of Mexico (except a
few restricted to single localities). Range maps are not provided
for introduced species or marine invaders. Production of range
maps relied heavily on state, provincial, and regional “fish books.”
A map shows the total range of a species based on historical
and recent records; that is, a map includes an area or drainage
even if that population is believed to be extinct. Within these
ranges, large gaps in distribution occur in ecologically unsuitable
areas. For example, the Rainbow Darter, Etheostoma caeruleum,
ranges over much of the eastern U.S. but lives in rocky riffles and
is absent from many areas within its range. Ranges in Mexico are
shown for U.S. species that narrowly extend into Mexico.
Maps for native species with transplanted populations include
areas where populations are known to be established. However,
species that are continuously being stocked—notably some
basses, sunfishes, and trouts—may be found almost anywhere in
the U.S. and southern Canada. The notation “Introduced elsewhere”
appears on maps for species that are likely to be found
outside the range shown. The reader should consult a species account
for additional information on geographic distribution.
Crosses between species occur occasionally in nature and are
especially common in sunfishes. Identifications of hybrids (as
species A x species B) usually are difficult. In making identifications,
keep in mind that hybridization occurs most often between
closely related species, and hybrids usually have characters intermediate
to those of parental species. As aquatic environments
degrade, hybridization increases, presumably because of difficulty
fishes have in recognizing spawning partners in turbid and polluted
Intergrade zones are areas where individuals (known as intergrades)
are intermediate in characters used in the recognition of
two subspecies. Intergrades may be intermediate because of the
mixing of genes (“gene flow”) of two subspecies or because of variable
environmental conditions leading to selection for characters
intermediate to those of two subspecies. Intergrades are named as
hybrids between two subspecies (e.g., Percina caprodes caprodes
x P. caprodes fulvitaenia).
How to Observe Fishes
You can watch fishes in clear water from stream banks and lakeshores,
and although at first they may all look the same or at best
as “minnows” or “sunfishes,” you can identify them by knowing
what species occur in the area and noting their distinguishing
morphological and behavioral traits. Binoculars and polarized
sunglasses that eliminate surface glare greatly facilitate fish
watching from above water.
Serious fish watchers enter water and join their subjects. With
a snorkel and mask, you can view fishes at amazingly short distances
and observe their feeding, spawning, and other behaviors.
Although fishes tend to swim away from humans on stream banks,
they remain close to a person underwater. Often, fishes are curious
and readily approach underwater observers.
In areas where many similar species occur, removing fishes
from the water may be the only positive way to identify them.
Many species can be obtained readily by seining, dipnetting, or
angling, and examined while on shore or transferred to aquariums
for long-term observation.
For most identifications, it is best to begin with the plates. Locate
the plate with fishes that look most like the one you wish to identify
(see “How to Use the Plates” on page 1), and read the short
descriptions of distinguishing features on the legend opposite the
plate. Arrows on plates pinpoint these features. When you believe
you have located the correct species, go to the longer text description
(page number given on legend page) and compare characters
of the fish with those given in the species account and, if necessary,
in generic and family accounts. “Similar species” sections
near the end of each account identify the most likely alternative(s)
to the species you selected and should be consulted before you
decide you have made the correct identification.
At some point, you will need to refer to the distribution map.
If you know from past experience that the fish you are working
with is one of a few similar species (e.g., a sand darter), you can
start with the maps. Eliminating species outside your area will
Fig. 1 illustrates various structures, counts, and measurements
used to identify fishes. Most are self-explanatory. The following
comments and the Glossary explain others.
Fishes have median fins (dorsal, caudal, and anal) and paired
fins (pectoral and pelvic). The dorsal fin in more ancient fishes
is supported by flexible, segmented “soft” rays. In more recently
evolved fishes, the front section of the dorsal fin contains only inflexible
spiny rays (“spines”) and may be contiguous with or separated
from the soft-rayed part; when the front section is separated
(or nearly separated) from the soft-rayed part, the fish is said to
have two dorsal fins. Likewise, the anal fin may be spineless or
have spines (usually only one to three) preceding rays.
Throughout the evolution of fishes, pelvic fins have tended to
move forward on the body, and their position is a quick way to
judge whether a fish belongs to a more ancient or a more recent
group. If pelvic fins are abdominal, the fish is a member of an ancient
group (e.g., sturgeon), and you can expect to find it near the
front of this guide. If the pelvic fins are thoracic (on the breast)
or jugular (on the throat), you will find the fish (e.g., a sunfish)
closer to the rear of the guide.
The mouth is described as terminal if it opens at the front end
of the head with the upper and lower jaws being equally far forward;
upturned if it opens above that point; and subterminal if it
opens on the underside of the head. You can see the rakers on the
first gill arch by lifting the gill cover (Fig. 2); a gill raker count is
the total for the entire first arch unless upper or lower limb only is
specified. The largest bone in the gill cover is the opercle (Fig. 1).
Measurements and counts used in this guide are shown in
Fig. 1. Measurements of body parts (e.g., snout length) or fins
occasionally are used to separate similar species. These measurements,
which are always made in a straight line (not along a
body contour), usually are compared with another measurement
(e.g., total length). A comparison such as snout length into total
length is made by dividing one measurement into the other, or by
physically “stepping off” one measurement into the other using
Lateral-scale count (also known as lateral-line scale count)
begins just behind the head and continues along the lateral line
(or along the midside if the lateral line is absent) to the origin
of the caudal fin (which is located by bending the caudal fin to
either side and noting the crease between the body and caudal
fin). Scales on the caudal fin are not included in lateral-scale
counts even if they are pored. Scales above and below the lateral
line begin at the origin of the dorsal or anal fin, respectively, and
continue diagonally to the lateral line (but do not include the
lateral-line scale). A transverse-scale count is a continuation of
the count of scales below the lateral line diagonally upward (including
the lateral-line scale) to the dorsal fin. Scales around the
caudal peduncle are those around the narrowest part. Predorsal
scales are those along the nape from the rear of the head to the
dorsal fin origin.
Fig. 3 shows how dorsal and anal rays are counted. In pectoral
and pelvic fins, all rays are counted. Branchiostegal rays are long
slender bones supporting branchiostegal membranes; all (short
and long) rays are counted.
To examine pharyngeal teeth, it is necessary to remove the first
pharyngeal arch by placing the fish on its side and lifting the gill
cover (if necessary, slit the skin along the bottom to loosen the
gill cover from the body). The arch lies just to the rear of the gills.
Insert a scalpel or strong forceps between the arch and shoulder
girdle, beginning at the upper angle of the gill opening and cutting
down along the shoulder girdle. Carefully sever the fleshy tendons
that hold the upper and lower ends of the arch in position, then lift
out the arch and remove the attached flesh to expose the teeth.
Pets, bait, and other fishes should never be released into a stream,
lake, or pond other than from where they were originally taken.
Non-native fishes and their offspring may outcompete or feed
on fishes or other organisms and do tremendous harm to native
No objective of this guide is more important than that of increasing
humanity’s appreciation of fishes and their environments.
We often fail to give adequate consideration to the vast and varied
forces over millions of years that have forged our present-day biodiversity.
Each species on Earth is the product of millions of years
of evolution and is fine-tuned to its environment. To conserve the
diversity of life, we must reduce our own population, reduce our
consumption, and set aside large ecosystems as preserves. We will
be able to accomplish those changes only through education and
an awareness of the value of diversity. It is our sincere hope that
this guide to the rich diversity of North American fishes will contribute
to that goal.