Catalogues of species on the web

There are several catalogues of species on the web. The frontrunner is Fishbase,  a database with a global reach that has a distinctly professional ichthyologist's and aquaculturist's slant to it. About 27,000 valid species and synonyms are represented, with a full range of references to the scientific literature stretching back to Linnaeus, with pics and scientific drawings, common names in many languages, maps, condensed details of spawning activities and other key data. There is a CD-ROM version that is even more detailed.
 
The growing Master Index of Freshwater Fishes maintained since 1996 by Ken Ruzek, now contains over 17,000 species, as well as an index to freshwater plants. There are references to more than 60 books and to articles in selected issues of six magazines, and links to FishBase. There are already over 600 images you can pull up. Of course, you'll still need to track down physical copies of the books mentioned in these references.
 
 An on-line version of William N. Eschmeyer's Catalog of Fishes, 1998, in 3 vols. is archived by the California Academy of Sciences. It is searchable. This was the most complete fish print reference ever put together, with about 26,000 valid species, and it is growing on-line at a rate of 200 to 300 species  each year. It's searchable by genus and species (you do have to know the scientific name of the subject of your search), and to get into the fish literature to trace down the references, you'd need a university biology library. But you should know about this first-class professional resource.
 
Hobbyist-oriented catalogues of fish species: these are some of the better lists.
 
Fish Profiles.
 
Fish Index. Utterly revamped in 2000, these Profiles, with photos, are partly a community effort, overseen by Kevin.
 
Planet Catfish.  Catfish, of course. Library of enlargeable thumbnail pix, web search capabilities.