Rhodactis Coral (Bullseye Mushroom)

 

• Common Name: Hairy Mushroom Coral, Tonga Mushroom, Bullseye Mushroom

• Scientific Name: Rhodactis spp.

• Class: Anthozoa

• Origin: Indo-Pacific, Australia, Red Sea, Fiji

• Category: Soft Coral

• Care Level: Beginner

• Temperament: Peaceful (but can spread aggressively)

• Lighting: Low to Medium (PAR 50-150)

• Flow: Low to Moderate (gentle, indirect flow)

• Placement: Bottom to Middle (best on rockwork or sandbed)

• Growth Rate: Fast

 

Overview:

Rhodactis mushrooms, commonly called Hairy Mushrooms or Tonga Mushrooms, are one of the most visually unique soft corals in the reef-keeping hobby. They are hardy, fast-growing, and easy to care for, making them an excellent choice for beginners. Unlike Discosoma, Rhodactis species have textured, fluffy tentacle-like structures that give them a “hairy” appearance.

Some Rhodactis mushrooms, like the Bounce Mushroom, are highly prized and can fetch premium prices due to their inflated vesicles that glow under LED lighting.

 

Tank Requirements & Water Parameters:

Rhodactis mushrooms are very adaptable and can tolerate a wide range of conditions, but they thrive best in stable environments:

• Temperature: 76-80°F (24-27°C)

• pH: 8.1-8.4

• Salinity: 1.024-1.026 SG

• Alkalinity: 7-10 dKH

• Calcium: 380-450 ppm

• Magnesium: 1250-1350 ppm

• Nitrate: 5-15 ppm (prefers moderate nutrients)

• Phosphate: 0.03-0.1 ppm

Unlike stony corals, Rhodactis corals prefer moderate nutrients and can thrive in tanks that are not ultra-low nutrient (ULNS) systems.

 

Lighting Needs:

• Low to moderate lighting (PAR 50-150) is ideal.

• Higher lighting may cause Rhodactis to shrink or “deflate” over time.

• They glow best under actinic or blue spectrum lighting, making them a popular choice for nighttime fluorescence.

If a mushroom starts moving away from its placement, it may be receiving too much light.

 

Flow Requirements:

• Low to moderate flow is best.

• Too much flow can cause Rhodactis mushrooms to detach and drift around the tank.

• They thrive in gentle, indirect currents where they can expand fully.

 

Feeding & Nutrition:

While Rhodactis mushrooms contain zooxanthellae and can survive on photosynthesis alone, they benefit greatly from supplemental feeding.

• Ideal Foods:

• Phytoplankton

• Reef amino acids

• Powdered coral foods (e.g., Reef Roids, Coral Frenzy)

• Finely chopped Mysis shrimp, brine shrimp, or fish eggs

Feeding 1-2 times per week can enhance growth, color, and polyp expansion. Some species can even engulf large prey, making them more carnivorous than typical mushrooms.

 

Placement & Aggression:

• Placement: Bottom to middle of the tank, often on live rock or rubble.

• Aggression: Peaceful, but they can spread aggressively and overgrow neighboring corals if left unchecked.

Tip: If you want to contain their spread, place them on an isolated rock or “mushroom island” to prevent them from overtaking the tank.

 

Growth & Propagation:

Rhodactis mushrooms grow quickly and reproduce in several ways:

1. Natural Division: A single mushroom splits into two or more over time.

2. Pedal Laceration: Small fragments left behind will regenerate into new mushrooms.

3. Manual Fragging:

• Use a sharp razor or scalpel to cut a mushroom into sections.

• Each section will regenerate into a full polyp within a few weeks.

• Attach frags to rubble using a rubber band or mesh until they adhere.

 

Popular Color Morphs & Variations:

Rhodactis mushrooms come in an incredible variety of colors and patterns, including:

• Rainbow Rhodactis – A mix of fluorescent greens, reds, oranges, and blues

• Tonga Hairy Mushroom – Large, fluffy tentacle-like texture

• Superman Rhodactis – Bright red with neon blue streaks

• Green Rhodactis – Intense green hues, fluoresces under actinic lighting

• Blue Rhodactis – Deep blues with subtle patterning

• Bounce Mushroom – Features large, inflated, bubble-like vesicles, highly sought-after in the reef hobby

 

Challenges & Common Issues:

• Spreading too aggressively: Rhodactis can quickly take over a tank if left unchecked. Keep them on isolated rocks or in dedicated mushroom zones.

• Detaching from rockwork: If stressed by high flow or poor conditions, they may let go and float. Secure them until they reattach.

• Color fading: Usually caused by excessive light or ultra-low nutrients. Lower lighting and feed regularly to maintain vibrancy.

• Melting or shrinking: Sudden parameter swings or exposure to toxins (like chemical warfare from soft corals) can cause mushrooms to deteriorate.