Surely fish identification is as simple as comparing a fish to a picture in a book?
Although this is the easiest way to identify a fish, it does have some obvious drawbacks. The differences between some species are sometimes so subtle that they might not even show up on a photograph. There is often considerable variation within a species (called intraspecific variation) which can make a fish look unlike other members of its own species. Sub-species and geographic races can also exist, and there is a possibility that the fish pictured might not be a typical example of the species, which could lead you to believe you have a different fish. And with over 25,000 fish species, it’s equally likely that the fish may have been incorrectly identified – even if it appears in a book or magazine. Few of the popular books used for identifying aquarium fishes are 100% accurate…
