Species

A-Z of Fishes
Basic information about many species of fresh, salt, and brackish-water fish, grouped by family and listed by common name, as well as a message board devoted to the novice aquarist.
http://groups.msn.com/FishTheAZ

Class Actinopterygii
Taxonomy of the class known as bony fish, osteichthyes, ray-finned fish, or spiny-rayed fish, with profiles of representative species of each order and family.
http://animaldiversity.ummz.umich.edu/chordata/actinopterygii.html

FishBase
Searchable global database containing information on 25,585 species (110,000 common names), 71,000 synonyms, 28,000 photos, and 21,000 references.
http://www.fishbase.org