Assessor macneilli, commonly known as the blue devilfish or blue scissortail, is a small fish found in the southwest Pacific Ocean. It occasionally makes its way into the aquarium trade. This vibrant fish grows to a length of approximately 6 centimeters (2.4 inches) and boasts a purple-blue hue with long fins
Here are some interesting details about the Assessor macneilli:
- Description: It has a dark blue body with a thin paler blue edge on the dorsal, anal, and pelvic fins. The dorsal fin has 11 spines and 8-10 rays, while the anal fin has 3 spines and 9-10 rays. Its pectoral fins typically have 14-16 rays.
- Distribution: The blue devilfish inhabits the western Pacific Ocean, ranging from northeastern Australia and New Guinea through the Great Barrier Reef to New Caledonia.
- Habitat and Behavior: Found on reefs at depths of 2–20 meters (6.6–65.6 feet), it often groups together in shoals of up to 100 fishes in caves, crevices, and under ledges. Interestingly, it sometimes swims upside down. As a plankton feeder, its main diet includes crustaceans such as copepods, ostracods, and amphipods. The male of this species is a mouthbrooder, guarding the eggs in his mouth for 15–16 days until hatching occurs.
The scientific name, Assessor macneilli, was given by G.P. Whitley in 1935. While the genus name “Assessor” implies an assistant or helper, the specific name likely honors Whitley’s colleague, the carcinologist Francis A. McNeill of the Australian Museum, who probably assisted Whitley in his ichthyological collections.
