Unfortunately, this fish is often overlooked by aquarists due to its rather drab-looking coloration, thus, it’s often not readily found in the hobby, or at least at many LFS. Their coloration typically ranges from dark brown to a golden color, and more often than not, this fish is seen with a white blaze down its short snout. Our specimen changes color within these hues, but also develops lavender spotting that resemble coralline algae. According to Scott Michael, this species is sexually dimorphic, with females having single white blotches or spots above and below the lateral line, while males do not. Additionally, males have one or two white spots on the distal portion of their opercula which are absent in the female.
The most recognizeable trait of this fish is the large sail-shaped dorsal fin, which gives rise to some of its common names. This fish is distinguished from A. macaranthus by examining the starting point of the first dorsal spine. In the cockatoo, it begins behind the eyes whereas in A. macaranthus, it begins in front of the eyes.
Extremely laterally compressed, this fish will often sway in the current, where it resembles tumbeling seaweed. Do not mistaken it’s odd locomotion for disease.
What can we say about this species? We LOVE keeping it. They never seem to pay their tankmates much attention, but aren’t shy when it comes to feeding. It is also one of the most “friendly” fish we keep, coming out to greet us when we do tank chores, and even perching in my open palm on occasion.