Neodat Project http://neodat.org/
The Inter-Institutional Database of Fish Biodiversity in the Neotropics. Provides systematic and geographic data on neotropical freshwater fish specimens deposited in natural history collections.
Florida Museum of Natural History Ichthyology Collection http://www.flmnh.ufl.edu/fish/
One of the largest collections in North America, containing 143,000 computer-catalogued lots of fishes (about 1.43 million specimens) which are searchable online. Information about the collection, as well as a searchable database, informative shark research, and a rich photo gallery are available.
The Losey Lab http://www.hawaii.edu/loseylab
Learn about the ultraviolet (UV) world of coral reef fishes, including the effects of UV on: fish vision, coloration, behavior and ecology.
Brian W. Coad http://www.briancoad.com/
Ichtyologist's site includes a dictionary of ichthyology plus information on freshwater fishes of Iran and of Canada's National Capital Region.