Fishes of the world

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Fishes of the World


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Fishes of the World
Fourth Edition

Joseph S. Nelson
Professor Emeritus of Biological Sciences
Department of Biological Sciences, University of Alberta,
Edmonton, Alberta T6G 2E9
Canada


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This book is printed on acid-free paper.
Copyright © 2006 by John Wiley & Sons, Inc. All rights reserved.
Published by John Wiley & Sons, Inc., Hoboken, New Jersey.
Published simultaneously in Canada.
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Library of Congress Cataloging-in-Publication Data:

605

Nelson, Joseph S.
Fishes of the world / Joseph S. Nelson. - - 4th ed.
p. cm.
Includes bibliographical references and index.
ISBN-13: 978-0-471-25031-9 (cloth)
ISBN-10: 0-471-25031-7 (cloth)
1. Fishes - - Classification. I. Title.
QL618.N4 2006
597.01'2- - dc22
2005033605
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1


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Contents

605

PREFACE
ACKNOWLEDGMENTS
INTRODUCTION
PHYLUM CHORDATA
Subphylum Craniata
Superclass Myxinomorphi to Osteostracomorphi
Superclass Gnathostomata
†Class Placodermi, 35
Class Chondrichthyes, 39
Subclass Holocephali, 42
Order Chimaeriformes, 45
Subclass Elasmobranchii, 47
Order Heterodontiformes, 54
Order Orectolobiformes, 54
Order Lamniformes, 57
Order Carcharhiniformes, 60
Order Hexanchiformes, 64
Order Echinorhiniformes, 65
Order Squaliformes, 66
Order Squatiniformes, 68
Order Pristiophoriformes, 69
Order Torpediniformes, 71

ix
xiv
1
15
18
21–33
34

v


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Contents

Order Pristiformes, 73
Order Rajiformes, 73
Order Myliobatiformes, 76
†Class Acanthodii, 83
Class Actinopterygii, 87
Subclass Cladistia, 88

Order Polypteriformes, 88
Subclass Chrondrostei, 90
Order Acipenseriformes, 92
Subclass Neopterygii, 95
Order Lepisosteiformes, 97
Order Amiiformes, 98
Division Teleostei, 100
Subdivision Osteoglossomorpha, 102
Order Hiodontiformes, 103
Order Osteoglossiformes, 104
Subdivision Elopomorpha, 108
Order Elopiformes, 110
Order Albuliformes, 111
Order Anguilliformes, 114
Order Saccopharyngiformes, 124
Subdivision Ostarioclupeomorpha (= Otocephala), 126
Superorder Clupeomorpha, 127
Order Clupeiformes, 128
Superorder Ostariophysi, 134
Order Gonorynchiformes, 135
Order Cypriniformes, 139
Order Characiformes, 148
Order Siluriformes, 162
Order Gymnotiformes, 186
Subdivision Euteleostei, 189
Superorder Protacanthopterygii, 189
Order Argentiniformes, 190
Order Osmeriformes, 194
Order Salmoniformes, 199
Order Esociformes, 204

Superorder Stenopterygii, 207
Order Stomiiformes, 207
Superorder Ateleopodomorpha, 212
Order Ateleopodiformes, 212
Superorder Cyclosquamata, 214
Order Aulopiformes, 214
Superorder Scopelomorpha, 223
Order Myctophiformes, 223
Superorder Lampriomorpha, 226
Order Lampriformes, 226


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Superorder Polymixiomorpha, 230
Order Polymixiiformes, 230
Superorder Paracanthopterygii, 231
Order Percopsiformes, 233
Order Gadiformes, 235
Order Ophidiiformes, 243

Order Batrachoidiformes, 248
Order Lophiiformes, 250
Superorder Acanthopterygii, 260
Series Mugilomorpha, 262
Order Mugiliformes, 262
Series Atherinomorpha, 263
Order Atheriniformes, 266
Order Beloniformes, 276
Order Cyprinodontiformes, 282
Series Percomorpha, 293
Order Stephanoberyciformes, 294
Order Beryciformes, 299
Order Zeiformes, 304
Order Gasterosteiformes, 308
Order Synbranchiformes, 316
Order Scorpaeniformes, 318
Order Perciformes, 339
Order Pleuronectiformes, 442
Order Tetraodontiformes, 451
Class Sarcopterygii, 459
Subclass Coelacanthimorpha, 459
Order Coelacanthiformes, 459
Subclass Dipnotetrapodomorpha, 461
Order Ceratodontiformes, 464
Unranked Tetrapodomorpha, 465
Infraclass Tetrapoda, 466
APPENDIX
BIBLIOGRAPHY
INDEX

469
485
539


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Preface

One purpose dominated the writing of the previous editions of Fishes of the
World (Nelson, 1976, 1984, 1994): to present a modern introductory systematic treatment of all major fish groups, both fossil and living. The same objective
prevailed in writing this revision. The acceptance of the previous three editions
as a guide and reference to the classification of fishes by teachers of courses in
ichthyology or fish biology, collection managers, aquarists, and by ichthyologists and other zoologists in general has been increasingly gratifying. Many
important works have been published since the last edition (Nelson, 1994),

and we think we have a better understanding of relationships than we had a
decade ago; however, as in the past, only further work will enable us to judge
whether all of our new ideas are advances. Many questions remain. In this edition I have revised the classification in light of recent research, given references to recent systematic works, listed more genera under the families, and
given recent systematic information. Some new fish drawings have been added.
The introduction deals in an elementary way with various aspects of fish
diversity. In the main text, the lower chordates and fishes appear in linear
order in a manner that seems best to reflect their postulated evolutionary
relationships. I often present alternative schemes of classification from recent
literature. I have given categories down to at least family level and frequently
lower. Subfamilies are recognized in many families, but the stability or degree
to which we think they are monophyletic varies widely between and within
families. In some families the subfamilies appear to be well founded (e.g.,
Salmoninae). In others, some or all in a family may be weakly founded and
the composition of the nominal subfamily is likely to change (e.g., Characinae
and Gobiinae).
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I recognize a relatively large number of categories in order to provide a better presentation of postulated relationships. The categories used, and their
endings in parentheses when consistent, are as follows: phylum, subphylum,
superclass, grade, class, subclass, infraclass, division, subdivision, superorder,
series (these 11 categories are centered in the text), order (iformes), suborder (oidei), infraorder, superfamily (oidea), family (idae), subfamily (inae),
tribe (ini), genus, and subgenus. Not all categories are employed within a particular taxon. A dagger (†) denotes those taxa containing only fossil species;
it is usually given only for the highest appropriate taxon and not for the lower
extinct members of the group. Users who find the number of categories given
to be a cumbersome proliferation may wish to use only class, subclass, order,
suborder, and family (as given in the Appendix). Not all recognized (named)
taxa are assigned rank (e.g., placed in a named category) (the recognition by
named category of all branches in a cladistic classification would result in a
great proliferation of categories). The following are examples of some major
taxa that are part of the classification but for which no formal rank is assigned:
Vertebrates (formally the Vertebrata), Neoteleostei, and Acanthomorpha.
New in this edition is that a unique number is given for each order and family of living fishes (also given in the Appendix as in past editions) and a common name is given for each order.
For each family with living fishes, I give the most appropriate common
name that I know (only a few have been coined and, for some, only a vernacular version of the scientific name is given) and its general range. For many
families there is an outline drawing of a member, and sometimes more than
one; remember, however, there is much variation in body shape within many
of the illustrated groups. Although the outline drawings are based on actual
species, details of such variable features as scales are not shown in order to
keep the drawings generalized for the family. There is a short description for
each family and for many taxa in higher categories; some are inconsistently
brief, usually as a consequence of the lack of diagnostic features, especially
those features that are external or otherwise easily seen. I have often omitted
characters that are difficult to describe briefly, even if diagnostic for the
group. For some groups I explore differing areas of interest, rather than trying to produce a uniform but limited text. When given, the numbers of
abdominal and caudal vertebrae are placed in parentheses after the total vertebral number—for example, 25 (10 + 15). I often include interesting lifehistory or biological notes and the maximum length of the largest species.
When possible, the length is qualified by giving standard length (SL), fork
length (FL), or total length (TL). Also included are estimated numbers of recognized (valid) genera and species (in some cases the number of species in

each genus is also given). These figures are always for living forms—never for
fossils unless so stated. The degree of agreement with these figures by others
will vary from group to group (in part due to the subjective matter of lumping and splitting). For example, everyone would agree that there are but two
valid species of described percopsids, but one can find disagreement on the
number of valid described species of cichlids and gobiids that should be
recognized. I have tried to represent current but conservative thinking in


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arriving at these numbers. In many groups, undescribed species are known to
exist; these may be mentioned, but their number is not included in the
species total. Priority is given to literature published after 1994 in giving references in the family sections. Nelson (1994) should be referred to for much
of the literature forming the basis of earlier editions. I give examples of recognized generic names for each family; if the number is relatively small, I usually list them all. In choosing examples of generic names for large families, I
have tried to choose those that represent the following: (1) genera with many
species, (2) the type of a subfamilial category or that of a nominal family no
longer recognized, (3) genera whose species exhibit some extreme biological
diversity, and (4) genera whose species are commonly found or are important
in commercial fishery, sports fishery, or aquarium use. Generic synonyms are
usually given only for genera recognized as valid in Nelson (1994) but now

considered junior synonyms. No attempt is made to recognize all commonly
used junior synonyms, as these may easily be found in the very valuable
Eschmeyer (1998). I have used Eschmeyer (1998) to verify the spelling of
most of the names of extant genera, but time did not permit checking all.
I am assuming that a knowledge of fish anatomy, if not already acquired,
will be obtained elsewhere. In the osteological descriptions, I use the terms
circumorbital, infraorbital, and suborbital synonymously, and the lachrymal
(= lacrymal, lacrimal) is the first bone in the series—i.e., it is synonymous with
the first suborbital bone. However, proposals to change the name of some
bones from that used in previous editions as a result of our better understanding of homologies have not been adopted unless otherwise indicated.
For example, as noted in Janvier (1996), what are commonly termed
the frontals and parietals in actinopterygians, originally taken from human
anatomy, are homologous with the parietals and postparietals, respectively, of
early tetrapods.
I have made numerous minor and major changes to the classification presented in the previous edition. As in the last edition, I adopt a cladistic classification. This will provide users with some idea of the hypothesized sister-group
relationships and monophyletic groups, and it will help workers in all disciplines of comparative fish biology interpret their work in an evolutionary or
historical context. However, I have also tried to make only those changes that
seemed well founded. In order to keep the book within reasonable length, I
have not always given reasons for the decisions in making changes. However,
in preparing this edition I have again attempted to be relatively conservative
in making changes while, at the same time, accepting new and often radically different schemes, or parts thereof, within a cladistic framework when
they seem to be well founded. It is very naive to accept the latest proposals as
always being the best in postulating systematic relationships, regardless of the
method used and even if the study gives sound comparative information. All
new proposals should be critically evaluated. It is good to be innovative in systematic research, but I feel that changes in a classification such as this should
be made only when evidence is relatively strong. Of course, researchers in presenting new information will normally be advised to give the implications of
their work to classification.


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Preface

The 515 families with living species recognized in this edition represents an
increase from that in the previous three editions. This has resulted, in part,
from an increased practice to reject families that are clearly not monophyletic by placing taxa of uncertain familial affinity into separate families. However,
it continues to be my belief that in ichthyology we recognize more families
than is desirable for the benefit of the nonsystematist, although I do not
believe we should necessarily avoid recognizing monotypic families even if
their sister group is known. When cladistic relationships are better understood, we may be able to reduce the number of families to a more manageable number while expressing lower relationships with the increased use of
subfamily and tribe categories. I have attempted, within the above framework,
to keep the number of families from increasing even further and hope to
keep instability at the family level to a minimum.
As long as there are active, creative ichthyologists, there will be major disagreements in our classification in the foreseeable future (there is similar
disagreement in almost all important fields of biology). Fish classification is in
a dynamic state, and the student pursuing ichthyology will find that all groups
can be reworked. There are many challenges, both in developing the theory
of classification and in its actual practice. Because particular classifications
eventually become obsolete (as will most biological information), they should
be regarded as frameworks that will provide a basis for building as advances
are made. If, however, anyone questions the value of learning a classification,
it should be remembered that classifications are useful vehicles on which to

base an understanding of biology. We do not stop using objects or acquiring
the present state of knowledge merely because our technical information is
going to improve.
The primary task of the systematist is to seek an understanding of the evolutionary history of life. The systematist must also deal with such matters as
how to spell the names of taxa that have variant names in the literature—a
matter that sometimes tries one’s patience. It is surely frustrating and confusing, especially for the nonsystematist, to find differences in the spelling of
taxonomic names. There are still some problems in agreeing on how certain
family names should be spelled (e.g., in family names ending in -ididae vs.
–idae; see also discussion under family Lampridae--202). With regard to the
latter problem, there is some feeling that it may be more important to have
names pronounceable than to be grammatically correct. In this regard, a few
of us such as W. N. Eschmeyer and J. R. Paxton, while following provisions of
the “International Code of Zoological Nomenclature,” hope to arrive at some
agreement, eventually!
Although in this edition I have given a common name in English for every
family, I cannot state that we have agreement in family common names.
Eventually, with the help of such people as K. E. Carpenter and R. Froese, we
hope to produce a standardized common name for each family, mainly for the
sake of the nonsystematist. In this regard, such publications as Common and
Scientific Names of Fishes from the United States, Canada, and Mexico (Nelson et al.,
2004), FAO species identification guides (edited primarily by K. Carpenter),
other FAO publications, and FishBase (Froese and Pauly, 2003) are especially
useful.


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The ichthyologist is a student of fish systematics. A good grounding in many
of the sciences is necessary for the future ichthyologists to test the hypotheses
we have today. Ichthyology courses may be designed for students interested in
ichthyology or fisheries biology as a career and for the general biology student
wishing to learn something of those animals that comprise over one-half of
the vertebrate species. The laboratory section of courses usually demonstrates
the diversity of fishes and the probable course of evolution, shows systematically important characters, provides insight into how ichthyologists determine
which characters to use, and provides training in identification. Emphasis may
be given to the local fish fauna, and for this purpose there are many fine
regional books. However, it is desirable to have a broad look at fish classification and to place one’s local fauna in perspective to all fishes. Depending on
the time available, students may, for example, learn how to hypothesize
homologies, attempt to explain the biological significance of differences we
consider to be systematically important, and learn how morphology determines function and how ways of life can determine morphology. Fishes
provide good examples in showing how natural selection results in diverse
adaptations to common functions. Collecting trips, curatorial functions, and
special projects (e.g., skeletal preparation and clearing and staining specimens) may also be involved. The laboratory can be a good place to discuss taxonomic problems as well. The student of ichthyology must be well versed in
the methods and theories of systematic biology. An understanding of how systematic relationships are postulated (hypothesized) and knowing the
strengths and weaknesses of various approaches so that classifications can be
critically evaluated are far better than just learning the end results (which are
likely to be short-lived). Meetings such as those of the American Society of
Ichthyologists and Herpetologists, American Elasmobranch Society, American
Fisheries Society, Desert Fishes Council (dedicated to the preservation of
America’s desert fishes), European Congress of Ichthyology, Indo-Pacific Fish

Conference, International Meeting on Mesozoic Fishes, and the Society of
Vertebrate Paleontology provide excellent forums for learning and exchanging ideas. It behooves students of ichthyology, both apprentice and professional, to become actively involved in such groups.


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Acknowledgments

05

Many individuals helped me in various ways with the preparation of this edition. They are greater in number than given below. I am grateful to them all.
I greatly enjoy and benefit from seeing colleagues at meetings, from students to longtime friends (who sadly grow fewer in number as the years go
by). Valuable help was received over the years during visits to museums, and I
express my gratitude to museum curators who have been patient with overdue
loans while this work was completed. The working interactions, colleagueship,
and warmth provided at a 2004 FAO workshop is valued; I thank especially
Kent Carpenter, Michel Lamboeuf, FAO, and the staff at the Instituto Español
de Oceanografia Laboratory in Tenerife, Spain. I appreciate the thoughtfulness of researchers from around the world who have kindly sent me reprints
of their systematic works. I shall be grateful to those who send me referenced
corrections and materials for future revisions.
I have benefited from comments and information from many individuals,
including students, curators, researchers, and professors. It would be difficult to
know where to stop if I attempted to name them all. However, I am especially
grateful to Gloria Arratia, William E. Bemis, Bruce C. Collette, Kent E. Carpenter,

Bill N. Eschmeyer, G. David Johnson, Lynne R. Parenti, and Mark V. H. Wilson
who have shown strong support and provided help over many years. For reading
over selected sections and providing valuable comments I thank James Albert,
Wilson Costa, Marcelo de Carvalho, Brian Dyer, Eileen Grogan, Gavin Hanke,
David Johnson (special thanks to you, Dave), Dick Lund, John Maisey, Jack
Musick, Heok Hee Ng, Claude Renaud, Ken Soehn, and Mark Wilson.
For good ichthyological discussions helpful to preparing this edition and for
other valuable help and appreciated encounters, I thank M. Eric Anderson, Maria
Elisabeth de Araújo, Gloria Arratia, William E. Bemis, Tim M. Berra, Jack C.
Briggs, John C. Bruner, George H. Burgess, Kent E. Carpenter, Jeff C. Carrier,
Francois Chapleau, Bruce B. Collette, Sara Collette, Leonard J. V. Compagno,
Wilson J. E. M. Costa, Dominique Didier Dagit, Mrinal K. Das, Marcelo R. de
Carvalho, Mario C. C. de Pinna, William N. Eschmeyer, Rainer Froese, Carter R.
Gilbert, Nancy Gilbert, Lance Grande, Terry Grande, David W. Greenfield, Harry
J. Grier, Eileen Grogan, William Hamlett, Gavin F. Hanke, Sir Ronald A. Javitch,
Zerina Johanson, Maurice Kottelat, Dick Lund, John G. Lundberg, John G.
Maisey, Keiichi Matsuura, Rick L. Mayden, John E. McCosker, Bob M. McDowall,
John D. McEachran, Michal Miksik, Michael M. Mincarone, Masaki Miya, John F.
Morrissey, Jack A. Musick, Heok Hee Ng, Larry M. Page, Lynne R. Parenti, Nick
V. Parin, Colin Patterson (deceased), John R. Paxton, Ted W. Pietsch, E. Phil
Pister, Franciso J. Poyato-Ariza, Jack E. Randall, Claude B. Renaud, Tyson R.
Roberts, Ierecê L. Rosa, Richard H. Rosenblatt, Hans-Peter Schultze, Kwang-Tsao
Shao, Stephen H. Shih, Gerald R. Smith, Bill Smith-Vaniz, Victor G. Springer,
Melanie L. J. Stiassny, Hsi-Jen Tao, Bruce A. Thompson, Andrea Tintori, Jim C.
Tyler, Edward O. Wiley, and Mark V. H. Wilson. To the many others who know
they have helped but who are not mentioned, my thanks. I am thankful to the


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workers who made available the extremely helpful resources “Catalog of fishes”
(especially Bill Eschmeyer) and “FishBase” (especially Rainer Froese and Daniel
Pauly). I do not forget those who helped me in various ways with the previous editions, especially Carl L. Hubbs (deceased) and the staff at the Scripps Institution
of Oceanography. I value the earlier training from Peter Larkin (deceased), Don
McPhail, Tom Northcote (whose darkroom, with Heather’s help, led to greater
productivity), Ralph Nursall, and Norman Wilimovsky (deceased); I feel a special
indebtedness to Casimir Lindsey, teacher, scholar, artist, and friend.
I thank five anonymous reviewers for providing valuable comments in
reviewing my proposal of this edition; however, not all suggestions could be
incorporated in this edition.
I appreciate all those who helped with various technical aspects of preparing the manuscript. The Department of Biological Sciences of the University
of Alberta generously provided assistance and working space. Patrick Kong of
the Department of Biological Sciences prepared the four cladistic charts and
the two charts giving the sequence of classes and orders; most of the fish figures, new and old, were prepared by Pauly Wong. The help from Wayne
Roberts, collections manager of the University of Alberta Museum of Zoology,
is also appreciated. Valued assistance with the manuscript and computer challenges was provided by Claudine B. Nelson and Mark K. Nelson.
The staff at John Wiley & Sons have again, as from the start with the first
edition 30 years ago, been extremely helpful, in editorial, design, and production work, and it has been a great pleasure to work with them. In particular for this edition, I thank Jim Harper for his advice and faith in the book.
He and Scott Amerman were of immense help and it was always enjoyable
talking with them. I also thank Lindsay Orman.

Financial support of the National Research Council of Canada, Discovery
Grant #5457, was invaluable, primarily in allowing me to conduct research,
visit research museums, and attend ichthyological meetings.
I am grateful to Ed Crossman (deceased), Héctor Espinosa-Pérez, Lloyd
Findley, Carter Gilbert, Bob Lea, and Jim Williams, my fellow members on the
“Committee on Names of Fishes”, a joint committee of the American Fisheries
Society and the American Society of Ichthyologists and Herpetologists, in writing the 2004 book “Common and scientific names of fishes from the United
States, Canada, and Mexico.” Information acquired in writing that book was
helpful in writing this one.
One of my greatest professional joys was receiving the Robert H. Gibbs, Jr.
Memorial Award, 2002, for “An outstanding body of published work in systematic ichthyology,” American Society of Ichthyologists and Herpetologists,
presented July 8, 2002, in Kansas City, Missouri (coincidently, where my mother’s parents, the Schiesers, were married December 4, 1899). I am pleased to
have known Bob Gibbs.
Finally, I thank my wife, Claudine, and children, Brenda, Janice, Mark, and
Karen, and grandchildren, Anna and Kaitlind for making it all worthwhile—
a work I dedicate to the cherished memory of my parents, Walter Innes
Nelson and Mary Elizabeth Nelson (nee Schieser), brothers Walter and Bill,
and aunts Anne Sorenson (nee Nelson) and Alice Franks (nee Nelson).
--J. S. N.


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SEQUENCE OF CLASSES AND ORDERS (with ordinal number.family numbers used in text)

Actinopterygii

Saccopharyngiformes (26.89-92
Anguilliformes (25.74-88)
Albuliformes (24.71-73)
Elopiformes (23.69-70)
Osteoglossiformes (22.65-68)
Hiodontiformes (21.64)
Amiiformes (20.63)
Lepisosteiformes (19.62)

Polypteriformes (17.59)
Myliobatiformes (16.43-58)
Rajiformes (15.45-48)
Pristiformes (14.44)
Torpediniformes (13.42-43)
Pristiophoriformes (12.41)
Squaniniformes (11.40)
Squaliformes (10.34-39)
Echinorhiniformes (9.33)
Hexanchiformes (8.31-32)
Carcharhiniformes (7.23-30)
Lamniformes (6.16-22)
Orectolobiformes (5.9-15)
Heterodontiformes (4.8)

Myxiniformes (1.1)

Order

Petromyzontida
Myxini

Chimaeriformes (3.5-7)

Petromyzontiformes (2.2-4)

Class

Subphylum

CATEGORY

Craniata

Placodermi

Chondrichthyes

Acanthodii

Acipenseriformes (18.60-61)


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SEQUENCE OF CLASSES AND ORDERS (with ordinal number.family numbers (con’d))

Sarcopterygii

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Tetrapoda
Certodontiformes (62.513-515)
Coelacanthiformes (61.512)
Tetraodontiformes (60.503-511)
Pleuronectiformes (59.489-502)
Perciformes (58.329-488)
Scorpaeniformes (57.303-328)
Synbranchiformes (56.300-302)
Gasterosteiformes (55.289-299)
Zeiformes (54.283-288)
Beryciformes (53.276-282)
Stephanoberyciformes (52.267-275)
Cyprinodontiformes (51.257-266)
Beloniformes (50.252-256)
Atheriniformes (49.246-251)
Mugiliformes (48.245)
Lophiiformes (47.277-244)
Batrachoidiformes (46.266)
Ophidiiformes (45.211-225)
Gadiformes (44.212-220)
Percopsiformes (43.209-211)
Polymixiiformes (42.208)
Lampriformes (41.201-207)

Myctophiformes (40.199-200)
Aulopiformes (39.184-198)
Ateleopodiformes (38.183)
Stomiiformes (37.178-183)
Esociformes (36.176-177)
Salmoniformes (35.175)
Osmeriformes (34.172-174)
Argentiniformes (33.166-171)
Gymnotiformes (32.161-165)
Siluriformes (31.126-160)
Characiformes (30.108-125)
Cypriniformes (29.102-107
Conorhynchiformes (28.98-101)
Clupeiformes (27.93-97)


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Introduction

Fishes exhibit enormous diversity in their morphology, in the habitats they
occupy, and in their biology. This diversity is, in part, what makes understanding their evolutionary history and establishing a classification so difficult.
From hagfishes and lampreys to sharks, flatfishes, and lungfishes, they include

a vast array of distantly related vertebrates. Based on cladistic classification,
the ray-finned fishes, the dominant fish group in numbers of species, are
more closely related to mammals than they are to sharks. However, although
fishes are a heterogeneous assemblage, they exhibit phylogenetic continuity
(i.e., they are not a polyphyletic group).
Some people restrict the term “fish” to the jawed bony fishes, namely,
among living forms, the Actinopterygii, Latimeriidae, and Dipnoi. Many
would also include sharks, rays, and their relatives (a few sharks even have the
term “fish” in their common name, e.g., dogfishes). Some, as do I, also
include the jawless craniates: hagfishes and lampreys. If we wished to restrict
the term to a monophyletic group of what are conventionally called fishes, we
would apply it only to the actinopterygians (the ray-finned fishes). Therefore,
the term “fishes,” as used here, designates an assemblage that is a paraphyletic group (where the most recent common ancestor is included but all descendants from the common ancestor are not—in this case, the tetrapods are
excluded), not a monophyletic group (where not only the most recent common ancestor is included, but also all descendants from the common ancestor). We do not give the term “fishes” taxonomic rank. We use it as a matter
of convenience, essentially to describe those vertebrates studied by ichthyologists and covered in ichthyological courses. Despite their diversity, fishes

1


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Fishes of the World

can be simply, but artificially, defined as aquatic vertebrates that have gills
throughout life and limbs, if any, in the shape of fins.
The body of information known about fishes is vast and includes all facets
of biology. Fishes are attractive to researchers because of the wealth of information and diversity still to be found, both in fossil and living (extant) taxa,
including basic information on the world’s fish faunas. The field of ichthyology, the study of fish systematics, is enormously active and exciting. Many controversies and problems exist, and ichthyologists have numerous opportunities to make discoveries of new taxa, both extinct and extant, and to address
phylogenetic and biogeographic questions. This is an exciting time to be
studying fish systematics. Many male and female ichthyologists are increasing
our knowledge of fish relationships by conducting research on fossil and
extant fishes, and for the latter, using molecular and morphological techniques. Some studies are thankfully being done incorporating all such diverse
approaches in order to study the evolutionary relationships of fishes. In producing a classification of fishes, we critically examine the phylogenetic research
and show the relationships in a way that reflects what are thought to be the
most probable hypotheses. However, I feel it better serves the purpose of this
book to be more conservative in making changes than a primary researcher
should feel in showing the implications of new work.
A friendly word on the terms “fishes” and “fish” and on capitalizing their
common names: The term “fishes” is properly used when referring to individuals of more than one species. However, when one is referring to one or more
individuals of one species, the term “fish” is appropriate. Hence, it is correct to
refer to 100 Rainbow Trout as fish, but to two different trouts, such as one
Brook Trout and one Brown Trout, as fishes (the plural form Rainbow Trouts
is discouraged). The common names of the three species given in this example (which happen to be in three different genera) were capitalized. Although
I uphold the principles of common names in fishes established in 1960 by a
joint committee of the American Fisheries Society and the American Society of
Ichthyologists and Herpetologists, and explained in Nelson et al. (2004), I
deviate in one principle: in this edition the official common name of a species
is treated as if it were a proper noun (see Nelson, Starnes, and Warren, 2002).

NUMBERS

The species numbers of fishes given in the text, as in previous editions, are

intended to be conservative estimates of valid described species, not of all named
species nor of what might be undescribed. They are based, as far as possible, on
the latest taxonomic revisions of families and genera and the opinions of the specialists. I regard subspecies as a valid category, with subspecies as a taxon having
their own evolutionary history in allopatry and being important in management
and conservation efforts. They are not recognized in the species counts. I have
concern over efforts to raise, seemingly automatically, all subspecies to species
status; however, various workers have appropriately raised many subspecies to, or
back to, species status as they have become better understood. Many users will
find Eschmeyer (1998) and Froese and Pauly (2003), two Web-based sources that


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were not available in the first three editions, very useful, as do I, as guides to the
taxonomic literature and much more for all extant fish species.
Fishes constitute slightly more than one-half of the total number of approximately 54,711 recognized living vertebrate species. There are descriptions of an
estimated 27,977 valid species of fishes compared to 26,734 tetrapods. Many
groups of fishes are expanding with newly described species, whereas a few are
decreasing because species are being synonymized faster than new ones are
described. However, a net increase in species of fish is shown every year, and

the number of new species of fishes described annually exceeds that of new
tetrapods. The estimated number expected by the end of 2006 is 28,400. The
eventual number of extant fish species may be projected to be close to, conservatively, 32,500 (although a change in our species concept will alter this figure
and pose problems in making meaningful comparisons). In contrast to amphibians, mammals, and reptiles, the known diversity of living fishes exceeds that of
known fossil taxa. On the other hand, there is a much richer and more informative fossil fish record than there is for birds (even relative to their numbers).
Of the 515 fish families with living species recognized herein, the nine largest
(most species-rich) families, each with over 400 species, contain approximately
33% of all species (some 9,302). These families, in order of decreasing numbers
of species, are Cyprinidae, Gobiidae, Cichlidae, Characidae, Loricariidae,
Balitoridae, Serranidae, Labridae, and Scorpaenidae. Interestingly, about 66%
of the species (about 6,106) in these nine largest families are freshwater fishes,
whereas only about 43% of all fishes occur in or almost always in freshwater.
About 50% of all fish species are in the 26 most species-rich families (each with
222 or more species).
In the present classification, 64 families are monotypic, containing only one
species (33 have two species, in one or two genera), while 67 families each
have 100 or more species, three of which have over 1,000. Some 151 families
have only one genus (with a total of 587 species); the most species rich family with only one genus is the Astroblepidae with 54 species. The average number of species per family is 54, whereas the median number is only 12.
The approximate numbers of recognized extant families, genera, and
species in the 62 orders of fishes that contain living representatives is given in
the following table. The number of “freshwater species” is an estimate of the
species found only, or virtually only, in freshwater (or inland lakes, regardless
of salinity); these species may rarely occur in weak brackish water. This number excludes species that are usually diadromous as well as anadromous
species that may have landlocked populations. For all such species, the existence of only freshwater would have little or no direct effect on them. The last
column, “species using freshwater,” includes those species in the previous column plus those species frequently occurring in freshwater that may otherwise
be diadromous or simply entering freshwater in substantial numbers or in a
substantial portion of their range. The intent of the last column is to enumerate those species that either would not exist or whose range would be
markedly reduced if freshwater habitats were denied them. The category of
“Freshwater species” is presented solely to show habitat occurrence; it does
not imply biogeographic barriers or dispersal limitations.

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Order

Myxiniformes
Petromyzontiformes
Chimaeriformes
Heterodontiformes
Orectolobiformes
Lamniformes
Carcharhiniformes
Hexanchiformes
Echinorhiniformes
Squaliformes
Squatiniformes
Pristiophoriformes
Torpediniformes
Pristiformes
Rajiformes
Myliobatiformes

Polypteriformes
Acipenseriformes
Lepisosteiformes
Amiiformes
Hiodontiformes,
Osteoglossiformes
Elopiformes
Albuliformes
Anguilliformes
Saccopharyngiformes
Clupeiformes
Gonorynchiformes
Cypriniformes
Characiformes
Siluriformes
Gymnotiformes
Argentiniformes
Osmeriformes
Salmoniformes
Esociformes
Stomiiformes
Ateleopodiformes
Aulopiformes
Myctophiformes
Lampriformes
Polymixiiformes
Percopsiformes
Gadiformes
Ophidiiformes
Batrachoidiformes

Lophiiformes
Mugiliformes

Fishes of the World

Families

Genera

Species

Freshwater
Species

Species
Using
Freshwater

1
3
3
1
7
7
8
2
1
6
1
1

2
1
4
10
1
2
1
1
1
4
2
3
15
4
5
4
6
18
35
5
6
3
1
2
5
1
15
2
7
1

3
9
5
1
18
1

7
10
6
1
14
10
49
4
1
24
1
2
11
2
32
27
2
6
2
1
1
28
2

8
141
5
84
7
321
270
446
30
57
22
11
4
53
4
44
35
12
1
7
75
100
22
66
17

70
38
33
8

32
15
224
5
2
97
15
5
59
7
285
183
16
27
7
1
2
218
8
30
791
28
364
37
3,268
1,674
2,867
134
202
88

66
10
391
12
236
246
21
10
9
555
385
78
313
72

0
29
0
0
0
0
1
0
0
0
0
0
0
0
0

23
16
14
6
1
2
218
0
0
6
0
79
31
3,268
1,674
2,740
134
0
82
45
10
0
0
0
0
0
0
9
1
5

6
0
1

0
38
0
0
0
0
8
0
0
0
0
1
0
1
2
28
16
27
7
1
2
218
7
0
26
0

85
32
3,268
1,674
2,750
134
0
86
66
10
0
0
0
0
0
0
9
2
6
7
0
7