All fish / Plesiopidae

Blue Assessor

Assessor macneilli

Also known as blue devilfish, macneill's assessor, blue comet, blue assessor basslet, assessor basslet, yes, ブルーアセッサー, 蓝宝石七夕鱼

A small, solid deep blue reef fish with long rounded fins that often hovers upside down beneath ledges and overhangs. It is hardy, reef safe and less quarrelsome than many dottybacks, so it suits peaceful reef aquariums well.

Care at a glance

Care level

Easy

Temperament

Semi

Adult size

6 cm

Temperature

23 to 28 °C

pH

8.1 to 8.4

Smallest tank

110 litres

Keep as

Single, a pair, or a small group in a larger tank with plenty of caves

Diet

Carnivore: mysis, brine shrimp, chopped seafood, quality pellets and flakes

Swims

Middle of the tank

Lifespan

5 to 8 years

Water

Marine (saltwater)

Wild range

Western Pacific: Great Barrier Reef (Australia) and New Caledonia

Breeding

Males brood the eggs in their mouths after spawning in a cave, and the species has been bred in captivity. Raising the tiny larvae needs live rotifers and is moderately difficult.

Good to know

It can be territorial towards its own kind and similar cave-dwelling fish, so give each one its own shelter. Do not confuse it with the yellow and blue Assessor flavissimus.