BACK FROM THE DIVE, I wonder: what was that fish? I ask the guides and other divers, though it's the lazy way out. Next I browse the boat's book-shelf and dig out a selection of fish ID books. There are more fish than any of them individually could cover, so a fish I can't find in one may be in another.
Failing all that, if I have managed to get a photograph, back home I can try my own books.
Fishes of the Philippines by Genevieve Broad is not a book with which to travel - it's big and heavy. It is also not a book to browse through randomly and hope to come across the fish you have seen.
Where it excels is in the systematic identification of a fish, leading you through a series of stages to narrow it down from its overall shape, fin pattern, features, coloration, behaviour and habitat.
I tested the methodology on a couple of photographs taken the last time I was in the Philippines. It wasn't quick, but follow the instructions and it really does work.
Divers can't afford to buy every ID book, so how do you decide which to buy? Do you want it for the bookshelf or to travel with? Do you want to browse or follow a system? Does it look nice? That's what would settle it for me.
A book with more fish pictures taken under water rather than lifeless on a laboratory slab, as in this one, would also guide my spending.
John Liddiard

(Anvil Publishing, ISBN 9712713229). Hardback, 510pp, £46.50