Boulenger's anthias

Where they come from

Boulenger's anthias (Sacura boulengeri) are deepwater planktivores from the Western Pacific. Think Japan down through Taiwan and the Philippines, usually way below the recreational dive zone on steep reef slopes and drop-offs.

They hang in cool, very clear water with strong surge, popping in and out of ledges while picking off zooplankton. That deepwater background drives almost everything about how you keep them.

Setting up their tank

Give them room, shade, and flow. A single adult or pair can go in a 4-foot 90 gallon, but they really settle in a long 6-foot tank. For a harem (1 male, 4-8 females), think 125-180 gallons and up.

• Temperature: 68-73 F (20-23 C). A chiller is your friend.
• Salinity: 1.025-1.026 (35 ppt).
• pH: 8.0-8.3, stable.
• Flow: strong, mostly laminar across the front of the rockwork.
• Lighting: dim to moderate with shaded zones. Blue-heavy is fine, avoid blasting whites.

Aquascape tall, ledgy rock with caves and overhangs. They like a vertical face to hover in front of. Leave open water in front for schooling and feeding. Cover every gap on the top; they jump when spooked.

Oxygenation matters. Big skimmer, surface agitation, and healthy gas exchange. I run an airstone in the sump at night and keep the return pointed at the surface.

What to feed them

They have high metabolisms and tiny mouths. Small, frequent meals beat big dumps. I aim for 3-5 feeds per day early on, then settle at 3 once they are eating dry food.

• Frozen: calanus, cyclops, finely chopped mysis, enriched baby brine (to start), fish roe, finely minced seafood.
• Live (to kickstart new arrivals): enriched artemia nauplii, copepods if you culture them.
• Dry: tiny sinking pellets (0.5-1 mm). TDO, similar reef pellets, or high-protein micro granules.

Soak foods in HUFA/vitamin enrichers a few times a week. Turn off return flow for 5-10 minutes so the food hangs in the display and they get more time to pick it off.

How they behave and who they get along with

Peaceful midwater hoverers. In a group you will see a loose school cycling out into the flow to grab food, then retreating to the caves. They spook at sudden movement and bright light.

• Good tankmates: small fairy and flasher wrasses, gentle tangs (Kole, Tomini), Genicanthus angels, gobies, chromis that are not bullies, peaceful basslets.
• Use caution: big boisterous wrasses, aggressive Pseudanthias, dominant clownfish pairs, large angels that harass feeders.
• Reef safe with corals and inverts.

Keep one male per tank unless your system is enormous with multiple territories. A single male with several females works best. If you start with all females, the dominant one will turn male in a few weeks.

Breeding tips

They are protogynous hermaphrodites. In a stable harem, the top female becomes male and displays at dusk. Spawning is a quick rise-and-release in the water column.

• Run a dusk ramp on your lights to encourage courtship.
• Give vertical water space and gentle, steady flow so they can do short spawning runs.
• Collecting and raising eggs is specialized. Larvae are tiny and need live plankton (rotifers then copepods) and very clean, stable conditions.

Common problems to watch for

• Decompression damage from collection: buoyancy issues, bulging eyes, gas bubbles under skin. Buy from vendors experienced with deepwater fish and ask for a feeding video.
• Refusing food for days: try live foods, dim the lights, feed at dawn/dusk, and offer small items that hang in the water column.
• Overheating: temps above mid-70s F lead to rapid breathing and color washout. Use a chiller in warm climates.
• Low oxygen at night: gilling hard, hanging at the surface. Add surface agitation and run the skimmer wet.
• Parasites and disease: velvet/ich can wipe them out fast. Quarantine new fish, observe for flashing or clamped fins, and treat promptly. Flukes are common; a praziquantel round in QT helps.
• Intra-harem fighting: two males or a female transitioning can beat up subordinates. Remove extra males or increase hiding spots.