Great Sites for High Quality Photographs of Tropical Marine Species:
Snorkel StJohn - Great photography and long-term recording by Barbara Cites of so many species found in the US Virgin Islands.   An inspiration.
Ryan Photographic - Fantasic photography of marine species from around the world. Also Dr Ryan has given kind permission for us to use some of his images for illustrative purposes in the interim.  
Biological and Identification Sites:
FishBase - Scientific details on species. Extent of data varies between species. Also links to some images. Authoritative source.
Red List - Contains medium level biological data on most species found in Antigua. Use Scientific name in the Search facility. 
Marine Species Identification Portal - Low level information on species (using scientific names), but many species not in database. Some thumbnail images.
Smithsonian Tropical Research Institute
- High level identification details and multiple images, but no ecology/ life cycle data etc
Recommended Books:
Collins Pocket Guide - Coral Reef Fishes of the Indo-Pacific and Carribean Lieske and Meyers 2001 ISBN-13: 978-0007111114
Reef Fish Identification 3rd Edition: Florida, Caribbean, Bahamas (Reef Set (New World)) Humann and Deloach 2008 ISBN-13: 978-1878348302
Reef Creature Identification (Reef Set (New World)) Humann and Deloach 2013 ISBN-13: 978-1878348531
Reef Coral Identification (Reef Set (New World)) Humann and Deloach 2013 ISBN: 978-1-878348-54-8
Field Guide to Tropical Marine Fishes National Audubon Society1997. ISBN: 978-0-44601-9
SouthEastern and Caribbean Seashores  Eugene Kaplan Pederson Field Guides 1988 ISBN: 0-395-46811-6
Coral Reefs Eugene Kaplan Pederson Field Guides 1982 ISBN: 0-395-46939-2
Sea Stars, Sea urchins and Allies: Echinoderms of Florida and the Caribbean  1995 Gordon Hendler ISBN-13: 978-1560984504
Reef Fish Behavior: Florida, Caribbean, Bahamas 1999 Ned Deloach ISBN-13: 978-1878348289
A Field Guide  to Coastal Fishes - From Maine to Texas  Van Kells & Kent Carpenter  Johns Hopkins Press  ISBN 0-8018-9838-2