The same black and white fish over the same coral heads, and for most of a century the same species. This is the 🌊 Red Sea and western 🌊 Indian Ocean population of the humbug damselfish, separated out as its own species when genetic work showed the 🌊 Indian Ocean and Pacific forms had been apart long enough to count.
That is worth a card because it is not an exception. A great many of the fish on this reef were treated as Indo-Pacific species with enormous ranges, and as the genetics get done, one after another turns out to be a local species that merely looks like the Pacific one. The 🌊 Red Sea has been repeatedly isolated from the 🌊 Indian Ocean, and its fauna diverged during those closures.
For a diver nothing changes: it is a humbug over a coral head, it lives in a size-ordered group, and it drops into the branches when a shadow passes.
For a catalogue it changes everything, because the name on the card is the difference between a widespread fish and a regional one - and the second kind is what makes this fauna worth documenting separately.
The species. Dascyllus abudafur (Forsskål 1775) - from Abu-dafur Jabûd. ETYFish
- white with two broad black bars, essentially identical to the Humbug Dascyllus
- separated by range and by genetics rather than by appearance
- over branching coral in shallow water
- length up to 9 cm
