Bubble Coral (Plerogyra sinuosa)

Taxonomy & Identity

The Bubble Coral is one of the most distinctive LPS corals, featuring large, grape-like vesicles that inflate during the day for photosynthesis. At night, these bubbles deflate to reveal long, potent sweeper tentacles. This dual nature makes Bubble Coral both beautiful and surprisingly aggressive.

Natural Habitat & Distribution

P. sinuosa is found throughout the Indo-Pacific, from the Red Sea to the western Pacific islands. It typically inhabits protected reef areas, caves, overhangs, and shaded lagoon environments at depths of 3 to 35 meters. It prefers areas with gentle current and subdued lighting.

Morphology & Growth Forms

Bubble Corals form hemispherical or irregularly shaped colonies. During daylight, large bubble-like vesicles (modified tentacles) inflate to maximize light exposure for zooxanthellae. At night, these deflate and true feeding tentacles emerge. Colors include white, cream, green, and occasionally pink or blue-tinted varieties.

Lighting Requirements & Spectrum

• Intensity: Low to moderate
• Target PAR: 30–100

Bubble Corals prefer subdued lighting that mimics their natural shaded habitat. Too much light can cause the bubbles to remain deflated and may damage the tissue over time. Position in shaded areas or lower regions of the tank. They are excellent choices for caves or overhangs.

Flow Requirements & Patterns

• Intensity: Low
• Type: Very gentle, indirect

Low flow is essential for Bubble Corals. Strong currents prevent bubble inflation and can cause physical damage to the delicate vesicles. The bubbles should gently sway but not be pushed around aggressively. Protect from direct powerhead flow.

Nutrient Dynamics & Water Chemistry

Bubble Corals require stable water parameters. They are sensitive to rapid changes, particularly in alkalinity and temperature. Moderate nutrient levels are preferred. Pristine water quality with consistent parameters promotes long-term health.

Feeding Biology & Symbiosis

While Bubble Corals photosynthesize during the day through their inflated vesicles, they are also aggressive nocturnal feeders. Long sweeper tentacles emerge at night to capture prey and can take surprisingly large food items.

• Mysis and brine shrimp
• Small pieces of fish or shrimp
• Silversides and krill
• Coral pellets (placed near tentacles at night)

Feeding 2–3 times per week enhances growth and coloration. Target feed at night when feeding tentacles are extended for best results.

Common Diseases, Pests & Predators

• Brown Jelly Disease – particularly susceptible when stressed
• Tissue damage from physical contact with rock or other corals
• Bubble deflation from excessive light or flow
• Parasitic snails and flatworms (uncommon)

Handle Bubble Corals carefully as the bubbles are fragile and damage can lead to infection. Ensure stable placement where the coral won't be knocked against hard surfaces.

Compatibility & Placement

Despite their peaceful daytime appearance, Bubble Corals are highly aggressive at night. Sweeper tentacles can extend 6+ inches and pack a powerful sting. Give plenty of space to all neighbors.

• Best zone: Lower tank, shaded areas, caves
• Give space: 8+ inches from other corals
• Avoid: Placing near aggressive neighbors that might damage bubbles

Fragging Techniques

Bubble Corals can be fragged but require care due to their fragile nature. Use a dremel or saw to cut through the skeleton when bubbles are deflated (early morning works best). Each frag needs adequate skeleton and tissue. Allow extended healing time in very low flow conditions.

Aquacultured Strains & Trade Names

Most Bubble Corals are wild-collected, though aquaculture is increasing. Color varieties include white, pearl, green, and occasional blue or pink specimens. "Pearl Bubble" refers to specimens with iridescent white coloration. Green specimens with intense fluorescence are particularly desirable.

Difficulty Rating & Summary

Difficulty: Intermediate

Bubble Corals are unique and beautiful additions to reef aquariums but require specific conditions to thrive. Low light, minimal flow, and careful placement are essential. Their aggressive nature at night demands generous spacing. For aquarists who can meet their needs, Bubble Corals are fascinating and rewarding corals.