PREFACE 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 INTRODUCTION 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 909.  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. Names 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. Illustrations 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. Measurements 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. Accounts 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 species.  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 provinces.  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 Mexico.  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, and bedrock. 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. Maps 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. Hybridization 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 water.  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. Making Identifications 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 facilitate identification. Fish Morphology 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 dividers.  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. Conservation 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 populations.  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. Excerpted from Peterson Field Guide to Freshwater Fishes, Second Edition by Lawrence M. Page, Brooks M. Burr All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.