BBC
Bbc: World's Smallest Fish
This article reports on the identification of a fish that has set a new record as the world's smallest known vertebrate.
University of Florida
Florida Museum of Natural History: Most Commonly Asked Fish Questions
How many fish species are there? What is the world's largest and smallest fish? How long do fish live? How is the age of fish determined? You will find answers to these and other questions in this interesting site.