🐠 Randall's Assessor Basslet (Assessor randalli)
A Deep Blue-Black Body With Vivid Fins and Dark Spots • One of the Rarest Fish in the Hobby • A Natural Upside-Down Swimmer
 
📋 Randall's Assessor Basslet has a striking deep blue-to-black body with vibrant blue-edged fins and darker spots, sometimes taking on a dusky purple hue as it matures. Its colouration shifts dramatically with the viewing angle and the light, looking most vivid under whiter light. A note on identification: it's often mistaken for a dottyback thanks to its similar shape and colouring, but it belongs to a distinct family, Plesiopidae, alongside its Blue and Yellow Assessor cousins.
It comes from the Western Pacific, including reefs around Japan and the Philippines, where it lives in shallow, dimly lit reef spots at depths of roughly 1 to 6 metres. It's the third, lesser-known member of the Assessor genus, and it shares the family's charming upside-down swimming habit, often hovering beneath reef overhangs or within caves. It's one of the rarest fish in the hobby, rarely imported from the wild, so most specimens today come from captive-breeding programmes. Every Randall's Assessor Basslet we ship is feeding well.
It's fully reef safe and shy and reclusive when first introduced, growing more confident with time and the right aquascape. It's peaceful toward other species but territorial toward its own kind, so keep just one unless your tank is large enough for separate territories. It reaches about 7cm, so plan on at least 115L.
 
💡 Highlights
🎨 Deep Blue-Black With Vivid Fins: A colour that shifts with the light
💎 One of the Rarest Fish in the Hobby: Mostly captive-bred today
🙃 A Natural Upside-Down Swimmer: Hovers beneath overhangs and in caves
🌿 Fully Reef Safe: Won't harm corals or larger invertebrates
😌 Shy at First: Grows bolder with time and good aquascaping