Species guide
Nannochloropsis
Nannochloropsis is the dependable one. Two to three micrometres of indifference to imperfect care, an EPA-rich lipid profile, and densities that make green water practical — it is the species that keeps a live-feed room alive while the delicate species cycle.
- What it is
- A genus of very small, non-motile green microalgae — the workhorse of marine green water.
- Taxonomic group
- Eustigmatophyceae, not a true green alga despite the colour; N. oculata and N. gaditana are common in culture.
- Typical appearance
- Extremely small spherical cells, usually seen as a uniform dense suspension.
- Typical size
- Cells roughly 2–3 µm.
- Culture characteristics
- Among the hardiest cultured microalgae: tolerates broad conditions and reaches high densities. A thick cell wall protects it — and complicates digestion for some grazers.
- Major applications
- Green water for marine larviculture, rotifer production, EPA enrichment, copepod diet component, feed pastes.
- Typical users
- Marine fish and shrimp hatcheries, rotifer cultures, reef hobbyists, omega-3 and feed producers.
Why aquaculture values it
Nannochloropsis is the algae you keep when you cannot afford to lose the algae. It greens larval tanks, feeds rotifers that feed fish larvae, and adds EPA to copepod diets. Its tolerance of imperfect care makes it a recommended first marine species — see how to start a phytoplankton culture.
Nutrition and important compounds
Nannochloropsis is EPA-rich, which anchors its nutritional role; it is not a strong DHA source, so DHA-dependent programs pair it with Isochrysis or Pavlova. Its small, thick-walled cells suit some grazers better than others — in copepod culture it is usually part of a mix, not the whole ration.
A note on culture parameters
Nannochloropsis species and strains differ in salinity tolerance, temperature optimum and lipid content. Any published number should be traced to the strain and conditions it came from.
Frequently asked questions
Why is Nannochloropsis so popular?
Hardiness, high density, EPA content and small cell size. It is the species most likely to survive a beginner's learning curve.
Can copepods live on Nannochloropsis alone?
Some can; many do better on a mixed diet that includes flagellates, and its thick wall defeats some grazers. See our copepod culture comparison.
Is Nannochloropsis a green alga?
It looks like one, but taxonomically it is an eustigmatophyte — a different lineage with a very small chloroplast and no chlorophyll b.