Miyagi Tort Acro (WYSIWYG)

Acropora is one of the most well-known and widely kept types of stony corals in the reef aquarium hobby. It is part of the Acroporidae family, which contains a variety of species often referred to as branching corals or table corals. Acropora species are prized for their striking colors, fast growth rates, and delicate, branching, or table-like structures that mimic the appearance of tree branches or antlers. However, Acropora corals are also among the more challenging corals to care for, requiring specific water conditions and care.

Appearance

• Shape and Structure: Acropora corals exhibit a variety of growth forms, including branching, tabling, and bushy structures. Some species have fine, delicate branches, while others grow in wide, flat plates (called tables). The branches are often thin, but can grow in dense clusters or wide expanses, depending on the species.
• Colors: Acropora corals come in a range of vibrant colors, including blues, greens, purples, pinks, and even bright oranges and reds. These colors are often enhanced by the coral’s symbiotic relationship with zooxanthellae, the algae that live in their tissues and photosynthesize.
• Size: Some species of Acropora can grow relatively large, forming massive colonies, while others remain small and compact. As a general rule, Acropora corals can grow from a few inches to several feet in diameter, depending on the species and environmental conditions.

Natural Habitat

Acropora corals are native to shallow, tropical reefs throughout the Indo-Pacific region. They are commonly found in environments with strong currents and high light levels, such as outer reef slopes and back reefs. These corals are highly dependent on light and healthy water conditions to thrive and grow.

Care Requirements for Acropora Coral

Acropora corals are advanced-level corals that require stable and pristine water conditions to thrive. Below are the key factors you need to consider to successfully keep Acropora corals:

1. Lighting

• High-intensity lighting is essential for Acropora corals, as they rely on zooxanthellae (photosynthetic algae) to produce food via photosynthesis. In a reef tank, metal halide lights or high-quality LED lights that provide a spectrum of light, especially in the blue range (around 10,000 to 20,000 Kelvin), are ideal.
• Placement: Acropora corals should be placed in the upper half of the tank to ensure they get adequate light exposure. They need intense lighting but should be protected from direct, high-intensity light that could potentially bleach them.

2. Water Quality

• Stable water parameters are critical for Acropora corals. Consistency in parameters is often more important than exact numbers. Large fluctuations in water chemistry can cause stress, which may lead to the coral's decline.
  • Salinity: 1.024-1.026 specific gravity
  • Temperature: 74-78°F (23-26°C), but always keep it stable.
  • pH: 8.1-8.4 (stable pH is key for Acropora health).
  • Alkalinity: 8-12 dKH (a stable alkalinity helps with calcification).
  • Calcium: 380-450 ppm (this is essential for healthy skeletal growth).
  • Magnesium: 1250-1350 ppm (supports calcium balance and helps prevent issues with calcium precipitation).
  • Nitrate: Below 5 ppm is ideal (Acropora prefers low nutrient levels, especially nitrate and phosphate).
  • Phosphate: Below 0.03 ppm; high phosphate can lead to algae blooms and poor coral growth.

3. Water Flow

• Acropora corals thrive in moderate to high water flow. This ensures proper nutrient exchange, helps with the removal of waste, and prevents detritus buildup in the coral’s polyps.
• A strong current encourages the coral to grow in a healthy, branching structure. However, flow should be strong but not so direct that it causes physical damage to the coral tissue.
• In a reef tank, using a combination of powerheads and wave makers can create the optimal flow.

4. Feeding

• Acropora corals primarily rely on photosynthesis, but they can benefit from supplemental feeding. They can capture plankton and other small particles from the water, especially in a well-fed tank.
• Direct feeding is not typically required, but some reef aquarists feed their Acropora corals liquid foods designed for SPS (small polyp stony) corals, such as phytoplankton, zooplankton, or specialized coral foods.
• Ensure that your tank has an abundant plankton population, as Acropora can capture fine particles from the water.

5. Coral Placement and Space

• Acropora corals grow quickly and need space to spread out. It is essential to place them where they will not be crowded by other corals, as they can become aggressive and fight with nearby corals through sweeper tentacles.
• Acropora corals require adequate vertical and horizontal space to grow and thrive. Keep them away from corals that produce large amounts of toxins or have aggressive tendencies.

6. Maintenance

• Regular water changes: Performing weekly or bi-weekly water changes (10-20%) helps maintain stable water parameters, removing excess nutrients and replenishing trace elements.
• Calcium and alkalinity supplementation: As Acropora corals use calcium and alkalinity for growth, you'll need to supplement these elements regularly. This can be done via calcium reactors, liquid supplements, or two-part dosing systems.
• Monitoring: Regularly test water parameters, especially calcium, alkalinity, magnesium, and nitrate levels. Keep an eye on any signs of stress, such as bleaching (coral turning white), slow growth, or color loss.

Common Problems

• Coral Bleaching: When Acropora corals are stressed, they may expel their zooxanthellae, turning them white (bleached). This can occur due to sudden changes in temperature, light, or water chemistry. To prevent this, ensure consistent water parameters.
• RTN (Rapid Tissue Necrosis): This is a condition where the coral tissue begins to rapidly die, usually starting at the base and spreading upwards. It can be caused by a variety of factors, including poor water quality, physical damage, or bacterial infection.
• Acanthaster (Crown-of-thorns Starfish): These predators can damage or kill Acropora corals by feeding on them. Keep an eye out for starfish infestations.

Acropora in a Reef Tank

Acropora corals are the crown jewels of a well-established reef tank and, when properly cared for, can grow rapidly and color up beautifully. They are often used to create a vibrant "SPS reef" tank, filled with other small-polyp stony (SPS) corals, where they contribute to the overall biodiversity and aesthetic of the tank.

Acropora is an ideal choice for advanced aquarists looking to create a stunning, thriving reef system, but success depends on maintaining stable, ideal conditions. With proper care and attention, Acropora corals can thrive and grow into spectacular displays.