Corals don’t directly eat phytoplankton to grow, but phytoplankton play an important indirect role in coral health and growth, especially in reef aquariums or natural reef ecosystems.

Here’s how corals benefit from phytoplankton:

🌿 1. Fueling the Food Web

Phytoplankton are tiny photosynthetic organisms that are the base of the marine food chain. When added to a reef tank:

• Zooplankton and copepods (tiny animals) eat the phytoplankton.

• Many corals, especially LPS and NPS corals, eat zooplankton, copepods, or even the phytoplankton directly.

• This boosts available nutrition in the ecosystem, indirectly helping coral growth.

🌞 2. Supporting Symbiotic Zooxanthellae

Corals have a symbiotic relationship with zooxanthellae (microscopic algae) living in their tissues:

• These algae use sunlight to perform photosynthesis, providing sugars to the coral.

• Healthy water with good nutrient balance from phytoplankton helps support this photosynthetic process by stabilizing nutrient levels like nitrate and phosphate.