When we developed the FishBase concept, back in 1988, we had the notion that fish taxonomy was in a reasonably good state, that most names used in the literature would be correct, and that the rest could be dealt with through synonymies. While these assumptions were largely true, we dreadfully underestimated the remaining difficulties such as inconsistencies in recent publications, the necessity to keep track of and completely understand taxonomic works, and the sometimes detective-like work needed to assign a piece of information to the proper biological species.

Synonymies are difficult to read

Synonymies are difficult to read. This fact is largely ignored by non-taxonomists who tend to think that any name listed in a synonymy is an alias for the species in question. Unfortunately, taxonomic convention facilitates such thinking, by not forcing authors to highlight cases for which the above assumption is wrong; i.e., when the listed name actually is a valid name or synonym of another biological species, and it appears only in the synonymy because someone at some point confused the two species (see also, ‘The Role of Taxonomy’, this vol.). Some colleagues will know that such cases should be marked by a statement such as (‘non Lacepède’) following the species name. They may not be aware that¾ depending on the context¾ a comma, colon, or period following the species name might also flag misidentifications, i.e., names that are not aliases for the current name.

The most common¾ although usually harmless¾ confusion in reading synonymies is between the original author (such as in Scopelus dumerilii Bleeker 1856) and a subsequent user of the name who, e.g., assigned it to a different genus (such as in Diaphus dumerili Fowler 1928).

It was only when we started classifying synonyms into Status: original combination (e.g., Scopelus dumerilii Bleeker 1856); new combination (e.g., Diaphus dumerilii (Bleeker 1856)); misspelling (e.g., Diaphus dumerili (Bleeker 1856)); junior synonym (e.g., Myctophum nocturnum Poey 1861 of D. dumerilii); misidentification (e.g., Diaphus effulgens (non Goode & Bean 1896) of D. adenomus); questionable (needs further research); other (see Comment field); that we realized the many mistakes we ourselves had made when reading synonymies.

We ran numerous logical checks to deteck errors in the SYNONYMS table

We ran a number of logical checks to identify possible erroneous records, such as: list all synonyms that match valid names in the SPECIES table and are not classified as misidentifications; list all synonyms that point to more than one valid species; list all junior synonyms with the same specific name as the valid species to which they are attached; list all original or new combinations with an author different from the author of the valid name; list all synonyms with the characters ‘non’, ‘not’, or ‘nec’ in either the author or the comment field, and which are not classified as misidentifications; etc. Since FishBase 98, we have also compared all original descriptions and most junior synonyms with Eschmeyer’s (1998) Catalog of Fishes. We believe that, through this exercise, we have identified and repaired most errors.

Nomenclatural Changes
Scientific names are more than labels

Scientific names are more than labels in that they also reflect our current understanding of the evolution of fishes. Thus, all species in a given genus are thought to have a common ancestor, and no offspring of that ancestor must occur in another genus (i.e., the genus must be monophyletic). The same is true for the higher taxa of family, order and class, only that the common ancestor dates further back in time with each higher level.

Box 6. Chronology of species descriptions.

For zoologists, scientific taxonomy began with the publication, in 1758, of the tenth edition of C. Linnaeus’ Systema Naturae. The FishBase graph showing the number of fish species described since, here grouped in classes of 5 years (see Fig. 9), takes the same approach.

As might be seen, the graph depicts a see-saw pattern reflecting individual achievements (Linnaeus 1758; Bloch 1785; Lacepède 1798; Cuvier and Valenciennes 1828 ff; Günther 1859 ff.; and Boulenger 1909 ff.), showing a steady rise through the 19th century- the age of European colonial expansion- from about 50 to about 500 new species descriptions per 5-year period.

There is an interesting gap from 1880 to 1890, possibly caused by the fact that Cuvier, Valenciennes and Günther had described most specimens available in the collections (Tyson Roberts, Calif. Acad. Sci., pers. comm.). The graph also shows the devastating impact of World War I (1914-1918), and especially of World War II (1939-1945), when new species descriptions dropped to the level of the late 1700s.

Note that most of Linnaeus’ species are still valid today, because no previous descriptions could turn his names into junior synonyms. However, some of his names were found to point to the same species and were synonymized by the first revisers. Most of his names are now in different genera, thus reflecting our better understanding of the evolution of fishes.

Note also the high rate of duplicate descriptions from the early 19th to the mid-20th century, probably caused by a widespread rush to describe new species, coupled with inadequate access to published literature.


Bloch, M.E. 1785. Naturgeschichte der ausländischen Fische. Berlin, Vol. 1, 136 p.

Boulenger, G.A. 1909. Catalogue of the fresh-water fishes of Africa in the British Museum (Natural History). London. V. 1, p. i-xi + 1-373.

Cuvier, G. and A. Valenciennes. 1828. Histoire naturelle des poissons. Paris. Tome premier. 573 p.

Günther, A. 1859. Catalogue of fishes in the British Museum. London. Vol. 1. 524 p.

Lacepède, B.G.E. 1798. Histoire naturelle des poissons. Paris. 8 + cxlvii + 532 p.

Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae secundum Classes, Ordinus, Genera, Species cum Characteribus, Differentiis Synonymis, Locis. 10th ed., Vol. 1. Holmiae Salvii. 824 p.

Rainer Froese and Daniel Pauly

10% of the names change in 10 years

As ongoing taxonomic work continues to clarify relations between species, scientific names keep changing. In fishes, as a rule of thumb, about 10% of the names in any given work will be outdated after 10 years (Froese 1996, 1997). The unique way in which scientific names and references are linked in FishBase allows to trace such changes and to print a list of nomenclatural changes for major taxonomic works.


The SYNONYMS table contains more than 70,000 synonyms, including junior synonyms, new combinations, misspellings, misidentifications, and over 25,000 valid names. The information is drawn from references such as FAO Species Catalogues, regional checklists such as CLOFFA and CLOFETA, and family revisions such as Pietsch and Grobecker (1987).

Fig. 9. Species descriptions of fishes at 5-year intervals over time as contained in FishBase. See Box 6 for a discussion of this graph.


The table gives the synonymous Name, Author, the Reference and Page that state the classification or Status of the synonym (see choices above for Status), and a Comment field for further information regarding the name, author or references. Double-clicking on the Name and Author will give species and author information from Eschmeyer’s PISCES and REFERENCE databases, respectively; on the MainRef, the full citation of the reference; and, on the Comment field, a SEARCH window for finding full citation of references mentioned. Further information regarding original combination of the name may also be found by clicking on the buttons for Eschmeyer’s PISCES and GENERA databases. Additional buttons for About (Synonyms chapter in the manual), Glossary, Print and Status (internal codes and credits) are also provided.

How to get there

You get to the SYNONYMS table by clicking on the Synonyms button in the SPECIES table. You get to the Nomenclatural changes routine by clicking on the References button in the Main Menu. Eschmeyer’s SPECIES, GENERA and REFERENCE tables can also be accessed for reference in this table.


In the Web version of FishBase, click on the Synonyms link under ‘More information’ in the ‘Species Summary’ page to get to the information described in this chapter.


We thank Kent Carpenter for suggesting to classify synonyms as described above. We thank Susan M. Luna for her contributions to an earlier version of the SYNONYMS table. We applaud W.N. Eschmeyer for sorting out the above mentioned problems in his Catalog of Fishes (Eschmeyer 1998). We also congratulate Theodore W. Pietsch and David B. Grobecker for their excellent monograph on Frogfishes of the World (1987), which helped us to understand synonymies.


Eschmeyer, W.N., Editor. 1998. Catalog of fishes. Special Publication, California Academy of Sciences, San Francisco. 3 vols. 2905 p.

Froese, R. 1996. A computerized procedure for identifying misspellings and synonyms in checklists of fishes, p. 219. In D. Pauly and P. Martosubroto (eds.) Baseline studies of biodiversity: the fish resources of western Indonesia. ICLARM Stud. Rev. 23.

Froese, R. 1997. An algorithm for identifying misspellings and synonyms of scientific names of fishes. Cybium 21(3):265-280.

Pietsch, T.W. and D.B. Grobecker. 1987. Frogfishes of the world. Stanford University Press, Stanford. 420 p.

Rainer Froese and Emily Capuli