Bubble Coral Care Guide: Plerogyra Sinuosa Feeding and Placement

There is nothing quite like a bubble coral. When its grape-sized vesicles inflate under light, Plerogyra sinuosa transforms from a skeletal mass into a billowing, alien-looking sphere of translucent tissue. Equally fascinating is its feeding response — at night, the bubbles retract and long sweeper tentacles emerge to capture prey. This bubble coral care guide from Gensou Aquascaping at 5 Everton Park, Singapore helps you provide the right conditions for this unique LPS species.

What Makes Bubble Coral Unique

Plerogyra sinuosa is one of a small number of corals that dramatically change appearance between day and night. During daylight, large fluid-filled vesicles (the “bubbles”) inflate to maximise surface area for photosynthesis. After dark, these deflate, and the coral extends feeding tentacles that can reach 10-15 cm beyond its skeleton. This dual behaviour makes placement planning especially important — your bubble coral needs space that accounts for both its daytime volume and its nighttime tentacle reach.

Water Parameters

Bubble corals are relatively tolerant of typical reef conditions. Maintain salinity at 1.025, temperature between 25-27 degrees Celsius, alkalinity at 7.5-9.0 dKH, calcium at 400-440 ppm and magnesium at 1300-1400 ppm. They handle moderate nutrient levels without fuss — nitrate up to 15 ppm and phosphate up to 0.08 ppm rarely pose problems. In Singapore’s climate, cooling remains important, as sustained temperatures above 28 degrees Celsius can cause vesicles to remain partially deflated and tissue to appear stressed.

Lighting Requirements

Low to moderate light produces the best vesicle inflation. PAR values between 50-150 are ideal — much lower than what SPS corals demand. Under intense lighting, bubbles shrink and remain partially retracted, exposing the sharp, fragile skeleton underneath. Place bubble corals on sand beds, lower rock shelves or in shaded overhangs where they receive ambient light without direct exposure to your strongest fixture output.

A blue-heavy spectrum enhances the pearlescent quality of the vesicles and brings out subtle green or pink tints present in many specimens.

Flow and Positioning

Gentle flow is non-negotiable. The inflated vesicles are delicate, and strong currents cause them to press against the jagged skeleton beneath, resulting in tissue tears and potential infection. Position bubble corals in areas of low, indirect circulation — a sheltered nook in your rockwork or a flat area on the sand bed away from powerhead output. The vesicles should sway gently, never flatten or distort from excessive water movement.

Because the skeleton of Plerogyra is extremely sharp, handling during placement requires care. Use thick gloves and support the coral from beneath rather than gripping the vesicles. Physical damage to the bubbles can lead to bacterial infections.

Feeding: A Hungry Predator

Bubble corals are enthusiastic feeders and benefit greatly from regular target feeding. Offer mysis shrimp, enriched brine shrimp or finely chopped raw prawn two to three times weekly. The best approach is evening feeding, when sweeper tentacles are already deployed and actively searching for food. Simply place food items on the extended tentacles — the coral captures and consumes prey with surprising speed.

Regular feeding accelerates growth and improves vesicle inflation. Underfed bubble corals often appear deflated and pale, even when lighting and water chemistry are correct.

Aggression and Tank Mates

Despite their soft, benign daytime appearance, bubble corals are surprisingly aggressive at night. Sweeper tentacles pack a potent sting that damages or kills neighbouring corals within reach. Maintain at least 15-20 cm clearance from other species in all directions. SPS corals are particularly vulnerable to bubble coral stings. Only place other aggressive LPS species nearby if they can withstand or match the bubble coral’s reach.

Common Issues

Brown jelly disease occasionally affects bubble corals, presenting as a brown, slimy mass on the vesicles. Siphon off the infected material immediately and dip the coral in an iodine-based treatment. Strong flow impacting the vesicles is the most common trigger for tissue damage that precedes bacterial infections. Parasitic snails and flatworms may also target Plerogyra — inspect new specimens thoroughly and quarantine before adding to your display.

Persistent vesicle deflation during daytime usually signals excess light or excessive flow. Relocate the coral to a calmer, shadier position before investigating water chemistry.

A Showpiece Worth the Space

Bubble corals reward thoughtful placement with a display no other coral replicates. A well-sited Plerogyra sinuosa on a sand bed or lower shelf, its vesicles fully inflated under gentle blue light, creates an eye-catching focal point. Available for $20-$60 SGD at local marine shops around Singapore, bubble corals offer exceptional visual impact for a modest investment — provided you give them the calm, low-light environment they need.

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