Phytoplankton drives the bottom of the marine food chain in reef systems. Key strains: Nannochloropsis oculata (3-5 micron, filter feeders), Tetraselmis chuii (10 micron, copepod feed), Isochrysis galbana (5 micron, clam + larval food), Pavlova (DHA-rich). Uses: 1) feeding sponges, clams, and SPS coral; 2) sustaining copepod cultures; 3) raising larval fish + shrimp; 4) "greening" refugiums to outcompete nuisance algae. Hobby brands: Reef Nutrition Phyto Feast (live multi-strain), AlgaeBarn OceanMagik, BBcorals Phyto. Refrigerate live phyto, use within 4-6 weeks. Frozen alternatives: easier shelf life but slightly less effective for live filter feeders.
Reviewed by the Fast Aquatics husbandry team · Updated May 2026
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