Assessor macneilli, the blue devilfish[1] or blue scissortail, is a fish from the southwest Pacific Ocean. It occasionally makes its way into the aquarium trade.[2] It grows to 6 centimetres (2.4 in) in length. It is purple-blue with long fins.[3]
Description
Assessor macneilli is a dark blue fish which has a thin paler blue edge on the dorsal, anal, and pelvic fins. The dorsal fin has 11 spines and 8-10 rays, the anal fin has 3 spines and 9-10 rays and the pectoral fins have 14-16 rays.[4]
Assessor macneilli is found on reefs at depths of 2–20 metres (6.6–65.6 ft),[3] where it can group together in shoals of up 100 fishes in caves, crevices and under ledges,[4] where they often swim upside down.[3] It is a plankton feeder and its main food are crustaceans such as copepods, ostracods and amphipods. It is a mouthbrooder and the male guards the eggs in his mouth for 15–16 days, as hatching approaches the male keeps his mouth open continually and shifts the eggs backwards and forwards every 2–8 minutes.[4]