Blue Assessor (Assessor macneilli) Care Guide
Assessor macneilli is a small dark blue marine fish of the family Plesiopidae from the Western Pacific that lives in reef caves and swims upside down.
Overview
Assessor macneilli is a small dark blue marine fish described by Whitley in 1935. Native to the Western Pacific, it occupies reef caves and ledges and is also called the blue devilfish or blue scissortail.
Taxonomy
- Family: Plesiopidae
- Genus: Assessor
- Scientific name: Assessor macneilli Whitley, 1935
Habitat
The species ranges across the Western Pacific from north-eastern Australia and New Guinea through the Great Barrier Reef and Coral Sea to New Caledonia. FishBase records it as reef-associated at depths of 2 to 20 m in tropical water of 25-30 °C. It congregates in caves, crevices and under ledges, often swimming upside down, and can form groups of up to about 100 individuals.
Tank requirements
- Minimum tank volume: 100 L
- Temperature: 24-26 °C (75-79 °F)
- pH: 8.1-8.4
- Carbonate hardness equivalent: 8-12 °dH
- Lifespan: 5-10 years
Diet
It is a carnivore and planktivore, feeding on small crustaceans such as copepods, ostracods and amphipods. In the aquarium it accepts meaty foods offered twice daily.
Compatibility
The blue assessor is peaceful and uses the middle and cave zones of the tank. Reported suitable tankmates include clownfish, tangs, cardinalfish and wrasses. Keep it away from other small dottybacks in confined tanks and from predators such as lionfish.
Breeding
Assessor macneilli is an egg-layer that practises paternal mouthbrooding: the male guards the eggs in his mouth for about 15-16 days. FishBase notes that breeding in the aquarium is possible, though it is considered advanced.
Conservation status
IUCN Red List: Least Concern, assessed 20 April 2022.