Yellow Assessor

This species is native to the Western Central Pacific, particularly common along the Great Barrier Reef in Australia. It inhabits seaward reef slopes and vertical drop-offs at depths of 5 to 20 meters, living in loose schools inside dark caves and under ledges.

Member of the family Plesiopidae. Assessor flavissimus features an elongated, laterally compressed body with a deeply forked caudal fin. It grows up to 7 cm in length and has large eyes. It has a unique physiological adaptation allowing it to swim upside down.

Extremely peaceful, shy, and non-aggressive. In nature, it forms large colonies. In the aquarium, it can be kept individually or in small groups if introduced at the same time. It will not harass any tankmates and is easily intimidated by active fish.

The entire body displays a solid, brilliant lemon-to-golden yellow coloration. It features thin orange-red margins along the dorsal and anal fins, and a thin blue-violet ring around the iris of its eyes. No visible sexual dimorphism exists.

Requires a tank of at least 100 liters with plenty of live rock arranged to form caves, overhangs, and arches. Shaded areas and dim lighting will encourage it to swim in the open. The tank must be tightly covered as they may jump if startled.

Carnivorous planktivore. In captivity, feed high-quality frozen foods like mysis, enriched brine shrimp, copepods, and finely minced seafood. Over time, it will accept dry flakes and pellets. Feed twice daily in a quiet area of the tank.

Requires standard marine reef conditions: temperature at 22-27°C, pH at 8.1-8.4, salinity at SG 1.020-1.025, and KH between 8 and 12 dKH. Ammonia and nitrite must be kept at zero, with low nitrates and moderate water flow.

100% reef safe. It is completely safe with all corals and invertebrates, including small shrimp. Keep with peaceful tankmates such as firefish, gobies, cardinals, and peaceful clownfish. Do not house with aggressive or fast-swimming species.

Breeding has been achieved in captivity. They are paternal mouthbrooders. After spawning, the male carries a spherical egg mass in his mouth for approximately two weeks until hatching, during which time he does not feed.

The main risk is starvation due to stress from aggressive tankmates, which will cause it to hide constantly. Susceptible to marine ich (Cryptocaryon) under stress. Slow acclimation and a calm environment are vital for its success.