Pomacanthus imperator (Block, 1787)
Emperor angelfish, 40cm

The largest angel so far recorded from Kwajalein is the emperor angel, Pomacanthus imperator. It inhabits a variety of seaward and lagoon reefs, including lagoon-bottom shipwrecks. Usually solitary, we occasionally see them paired, possibly in preparation for mating. One interesting habit of this species is that it makes a loud grunting noise when approached too closely. Not infrequently, I first detect the presence of an emperor not by sight but by sound. Another large angel that we have not yet seen in the Marshalls but is reasonably common in the nearby eastern Carolines is Pomacanthus xanthometapon. It would not be surprising to see an occasional specimen show up here, but we have not yet heard of it actually happening.

I'm sure the one below is grunting away at the intruding photographer.

The two specimens below are small ones that have recently changed from their juvenile color pattern. You can tell because there are fewer yellow lines and they are not quite as straight and unbranching.

Juveniles look quite different from adults and are typically found only in a couple of different habitats. They are common in a series of manmade reef quarries dug out of the oceanside intertidal reef flat at Kwajalein Island. They are also found around isolated small reefs or obstructions on the sandy lagoon slope. Since they seem to grow up only in these two habitats, the adults inhabiting other areas of the atoll must swim to those places as they grow up.

The fish below is a small one that still has a trace of the underlying juvenile color pattern.

Created 16 September 2010

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