Tetraselmis is a vibrant green flagellated microalga loaded with essential fatty acids, amino acids, and phytonutrients. It's highly nutritious for copepods, rotifers, bivalves, and other filter feeders, which makes it a top-tier choice for marine aquarists and aquaculture setups.
What you'll need
- Tetraselmis starter culture
- F/2 fertiliser or similar nutrient blend
- Saltwater at 1.018 to 1.022 SG
- Strong full-spectrum light (6,500 to 10,000K)
- Air pump with rigid airline tubing
- Sterile container (plastic or glass)
Culturing steps
Prepare the culture medium. Mix RO/DI water with marine salt to roughly 1.020 SG. Add F/2 nutrients. Let it stabilise at room temperature (20 to 28°C).
Inoculate. Add your Tetraselmis starter culture. Swirl gently to distribute the cells evenly.
Aerate. Use gentle, steady aeration with a rigid airline. This keeps the cells suspended and oxygenated while preventing clumping.
Light it up. Provide 12 to 16 hours of bright light each day. Tetraselmis thrives under strong illumination and shows a rich green colour when healthy.
Monitor growth. Within 5 to 7 days, the culture should turn visibly green and slightly thicker. A healthy culture smells fresh, not rotten or sulfuric.
Harvest. Use a fine mesh sieve or decant gently. Refrigerate any unused portions and keep backup cultures running so you don't get caught out if one crashes.
Tips for success
- Tetraselmis is motile. Steady aeration prevents it from settling out at the bottom.
- It's less tolerant of poor conditions than Nannochloropsis, so cleanliness matters more here.
- Always sanitise equipment between batches to keep contamination out.
Why culture Tetraselmis?
- Solid nutrition. Good amino acid profile, plus EPA and other fatty acids.
- Pod and rotifer enrichment. Boosts the nutritional value of any zooplankton you raise on it.
- Useful for larval fish stages. Cell size and softness suit early-life diets.
- Improves microfauna health. Stronger reproduction and better survival across the food web.
Whether you're feeding a pod population or enriching live foods, Tetraselmis delivers balanced, complete nutrition in every drop.
