Fish ID books are great, but now that divers and
photographers are bringing laptops on dive trips, let us
suggest this digital fish ID source, Fishes of the Caribbean
and Adjacent Waters. It's a superb addition for any digital
diver's computer library.
This interactive field guide comes in CD-ROM or
  DVD format and includes descriptions of 665 species
  accompanied by 2,500 color photos and 1,000 video
  clips of most common species in their native habitats.
  Ichthyologist Dr. John Randall, himself an author of
  fish ID books, calls it "comprehensive, informative,
  meticulous in its detail, and fun to use."  
The Premium DVD edition includes software for
  PCs, and can be used in any DVD player or DVD-ROM
  disc drive running on Windows. The package includes
  minimal instructions, so I needed a little help from the
  publisher (ReefNet, of Ontario, Canada), to install it
(1.4 gigabytes). 
I printed out the PDF operating manual to help
  navigate the complex software with features such as
  a species browser and detailed species descriptions
  accompanied by photographs, sketches, and audio
  pronunciations of scientific names. Video content was
  beautifully shot, with sound effects and background
  music. The most helpful feature was a search engine
  that allowed me to look up, say, a splendid toadfish
  by selecting among preset descriptions of markings, anatomical features (e.g., barbels) and behavior. The
descriptive terminology was defined in a glossary just
one tab-click away. Indeed, the disk makes identification
and fact finding a breeze.

Other interactive tools include a flash-card fish quiz
  customizable for the user's skill level, a log for recording
  sightings, an illustrated glossary of scientific terms,
  an interactive map of the Caribbean and a multimedia
  show designer for custom presentations.  
The premium DVD lists for $75, but you can order
  it through Undercurrent at a discount by going to Undercurrent. If your PC doesn't have a DVD
  drive, you can opt for a CD-ROM version containing
  the software system, photos, video clips, detailed
  descriptions and many interactive features ($70). You
  can also order directly from ReefNet at 1-888-819 REEF.