Ophiarachna incrassata

Acclimation: it does not take well to fluctuating water parameters. Acclimate it slowly by drip and avoid any copper treatment.

Setup: it grows large and needs plenty of rockwork to hide in. Reef Builders suggests at least 50 gallons (about 190 L) for a large specimen; Reeflex even recommends 1000 L.

Tankmates: it leaves corals and anemones alone but catches small fish and mobile invertebrates at night, especially ornamental shrimps and crabs right after moulting. Avoid small bottom-dwelling fish (Catalina gobies, Lythrypnus dalli, for example) and choose fish slightly too large for it. Quality Marine also advises against decorative clams, a favourite food of large specimens. Snails and hermit crabs can live with it, but it eats them once they die.

Predators: do not keep it with big triggerfish, tuskfish (Choerodon) or pufferfish, which would eat it. A well-fed specimen hunts less, according to some hobbyists, but remains an opportunist.

Water: aim for 22 to 25.5 °C, a specific gravity of 1.023 to 1.025, pH 8.1 to 8.4 and 8 to 12 dKH. Quality Marine rates it 'easy'; Reeflex reserves it for advanced hobbyists.

In the wild it mostly eats bottom-dwelling invertebrates, but also carrion, detritus and occasionally small fish it traps.

In the aquarium it is not fussy: it accepts almost any food offered to fish and eats detritus. Quality Marine feeds small bits of thawed marine meaty food (krill, chopped prawn, cockle) once or twice a week, which is enough even in a small tank. An underfed specimen may overpower small fish.