Metallic Green Star Polyp Coral (GSP)

Overview

The Metallic Green Star Polyp Coral, commonly known as GSP, is a popular soft coral recognized by its vivid metallic-green polyps and contrasting purple or reddish encrusting mat. When fully extended, the polyps create a bright, grass-like appearance that adds movement and intense color to the reef aquarium.

Green Star Polyps are hardy, fast-growing, and adaptable to a wide range of aquarium conditions. They can rapidly spread across rocks, aquarium walls, overflow boxes, and other hard surfaces, making them an excellent choice for decorative coral islands or background coverage.

Care Requirements

Lighting and Water Flow

Metallic Green Star Polyps adapt well to low to moderately strong reef lighting. A PAR range of approximately 50–150 is suitable for most colonies. Brighter lighting may encourage more compact growth and stronger coloration, while insufficient lighting can result in reduced extension or duller appearance.

Provide moderate to strong, indirect, and variable water flow. Good flow helps keep sediment and detritus from collecting on the coral’s mat and encourages the polyps to extend fully. Avoid placing the coral directly in front of a powerful pump, as constant concentrated flow may prevent normal polyp extension.

Aquarium Placement

Green Star Polyps can be placed in the lower, middle, or upper areas of the aquarium, depending on lighting intensity and water movement. Secure the coral on stable rockwork or another hard surface where it can spread naturally.

Because GSP grows rapidly, it is often best placed on a separate rock island away from the main aquascape. This makes its growth easier to control and reduces the risk of it covering slower-growing corals.

Recommended Water Parameters

Feeding

Metallic Green Star Polyps contain symbiotic zooxanthellae and obtain most of their energy through photosynthesis. Direct feeding is generally not required when the coral is kept under suitable lighting and in a stable reef aquarium.

The colony may absorb dissolved nutrients and capture very fine suspended foods from the water column, including:

• Fine phytoplankton preparations.
• Very small zooplankton-based coral foods.
• Dissolved organic nutrients.
• Fine particles released during normal fish feeding.

Avoid excessive feeding, as Green Star Polyps normally grow well without regular target feeding and additional food may unnecessarily increase nutrient levels.

Compatibility and Growth Control

Metallic Green Star Polyps are generally considered peaceful in terms of stinging ability, but their extremely fast growth makes them highly competitive. The spreading mat can grow over nearby rocks and may eventually cover or shade slower-growing corals.

Leave adequate space around the colony and trim back the mat whenever it begins approaching neighboring corals. Regular maintenance is especially important when GSP is attached directly to the main rock structure.

Acclimation

Acclimate the coral gradually to the aquarium’s water conditions and lighting. Begin in an area with moderate lighting and indirect water flow, then adjust its position based on polyp extension and coloration.

Green Star Polyps may remain closed for several hours or even a few days after transport, handling, fragging, cleaning, or changes in water conditions. This is often temporary, provided the mat remains firm and free from tissue deterioration.

Signs of Good Health

• Regular and full polyp extension.
• Bright metallic-green coloration.
• A firm purple or reddish encrusting mat.
• Steady expansion across nearby hard surfaces.
• No peeling, discoloration, excessive algae, or tissue breakdown on the mat.