Common Name: Chagos Skunk Anemonefish
Scientific Name: Amphiprion chagosensis Allen, 1972
Distribution: Chagos Archipelago
Type Locality: Diego Garcia Atoll, Chagos Archipelago
Identification: Two vertical white stripes, both relatively thin, the anterior stripe often broken dorsally. Body dark in color, ranging from an orange-brown to a nearly black shade. Pelvic and anal fins dark. Spinous dorsal fin dark, becoming clearer posteriorly. Caudal fin clear, but tinged the same color as the body.
Similar: Most commonly confused with the sympatric A. cf clarkii population, which also has two stripes. That fish has thicker stripes, yellow fins and is never darkly colored as with the true A. chagosensis. It also occurs in a broad range of anemones. Juveniles of these two differ considerably, with A. chagosensis lacking the pennant-like extension of the middle stripe onto the dorsal fin and the black and white patterning on the caudal fin seen in A. cf clarkii.
Notes: Known only from the Magnificent Sea Anemone (Heteractis magnifica). The presence of predorsal scales and its host anemone preference clearly places this fish among the skunk anemonefishes, though previous classifications have erroneously put this species within a broadly defined clarkii group.
There is reason to believe that this species arrived upon its unique appearance due to regular hybridization with the sympatric A. cf clarkii. The two are easily confused and often misidentified. While they typically occupy separate anemones, an image shown below illustrates a large A. cf clarkii alongside two juvenile A. chagosensis in a Magnificent Sea Anemone.
This is one of the rarer Amphiprion species and has likely never been collected for aquarists. However, an individual which bears all the hallmarks of this species did appear at B-box Aquarium in Japan. It’s possible this was a waif to the Maldives, a hybrid with A. nigripes, an A. nigripes with an atavistic mutation, or, perhaps, an illegally collected specimen originating from Chagos.