The short answer is to get permission or use royalty free stock images.
Copyright protection is automatically added to images published online and fair use seems to be a complex subject. Proper attribution and linking of the images back to the original isn’t enough either, unless it is under creative commons. But most creative commons images are generally specified for non-commercial use. What happens if there is an advertisement on the webpage that the image is displayed? What if the image is on the same site that happens to sell something on another page within that site? There seems to be no definitive answer to that, just peoples opinions.
So this leaves us in a bit of a pickle.
We could re-illustrate every fish. But realistically I’d sooner try cutting my toenails with an angle grinder then sitting and redrawing hundreds of fish. And the results wouldn’t have the same effect as a really decent photograph.
We could just go ahead and use images without permission and plead ignorance if we’re found out. Tempting, but no. Besides, the existence of this post would negate that defense.
So the plan? Have a look and see what we can find on Flickr under creative commons with commercial use. The next step is to go through the stock image sites and see what we can find and hopefully pay for. What we can’t find there we’ll try source from kindhearted divers that happen to have the shots we need *Nudge Nudge* (Credit will be displayed along with the image!). Failing all this we’ll have to go and hunt the needed critters down and take our own shots.
For now? We’ll be going through Flickr and the stock libraries and using the watermarked images as placeholders. Good a place as any to begin.