Nannochloropsis oculata - The Gold Standard Marine Microalgae for Reef Aquariums and Commercial Aquaculture

Scientific Classification & Taxonomy

Kingdom: Chromista | Phylum: Ochrophyta | Class: Eustigmatophyceae | Order: Eustigmatales | Family: Monodopsidaceae | Genus: Nannochloropsis | Species: N. oculata

Complete Nannochloropsis oculata Profile for Aquaculture

Nannochloropsis oculata represents the most widely cultivated marine microalgae species in saltwater aquarium hobby and commercial aquaculture operations worldwide. This single-celled marine phytoplankton species measures 2-4 micrometers in diameter, making it an ideal live food for copepods, rotifers, brine shrimp, and filter-feeding reef aquarium invertebrates including corals, clams, and sponges. The microscopic size allows direct consumption by coral polyps and zooplankton at all life stages.

The genus name "Nannochloropsis" derives from Greek roots meaning "small green appearance," referring to the microscopic size and distinctive green coloration visible in dense cultures. This marine microalgae belongs to the Eustigmatophyceae class, characterized by the absence of chlorophyll b and large amounts of chlorophyll a. Under optimal conditions, Nannochloropsis can achieve cell densities exceeding 10-20 million cells per milliliter, producing extremely dense, dark green cultures that appear almost black.

Nutritional Composition of Nannochloropsis oculata

Protein Content: 35-50% dry weight - Contains all essential amino acids including lysine, leucine, valine, isoleucine, threonine, phenylalanine, methionine, histidine, and tryptophan required by marine organisms.

Lipid Content: 20-35% dry weight - Most significantly, EPA (eicosapentaenoic acid) comprises 24-39% of total fatty acids, representing one of the highest EPA concentrations in any easily cultured microalgae. EPA serves essential functions including regulating inflammation, supporting cardiovascular health, enhancing immune function, promoting neural development in fish larvae, and supporting reproductive success in copepods.

Carbohydrates: 15-25% dry weight - Primarily storage polysaccharides providing energy reserves.

Pigments: High chlorophyll-a concentrations plus violaxanthin, vaucheriaxanthin, and carotenoids contributing to characteristic coloration and providing antioxidant benefits.

Vitamins & Minerals: Rich in B-complex vitamins (thiamine, riboflavin, niacin, B12, biotin), vitamin C, vitamin E, and essential trace minerals including iron, manganese, zinc, copper, selenium, and iodine.

Marine Aquarium Applications

Live Coral Food & Reef Tank Nutrition: Nannochloropsis oculata serves as premium phytoplankton for virtually all reef corals. SPS corals including Acropora, Montipora, Stylophora, Pocillopora, and Seriatopora benefit tremendously from regular supplementation. The 2-4 micrometer cell size allows direct capture by tiny polyps, providing essential fatty acids, amino acids, and pigments that enhance coloration, accelerate growth rates, improve tissue density, and promote overall health.

LPS corals including Euphyllia (torch, hammer, frogspawn), Trachyphyllia (open brains), Cynarina (button corals), Scolymia, Acanthastrea, and Lobophyllia also consume Nannochloropsis actively. Regular feeding supports tissue expansion, enhances feeding responses, improves color intensity, and accelerates recovery from stress events.

Soft corals including leather corals (Sarcophyton, Sinularia), pulsing Xenia, and zoanthids benefit despite symbiotic zooxanthellae. The particulate feeding provides supplemental nutrition supporting growth and reproduction. Tridacnid clams (maxima, crocea, derasa, gigas, squamosa) actively filter-feed throughout their lives, with juveniles particularly benefiting before zooxanthellae populations fully develop.

Feather duster worms, Christmas tree worms, sea squirts, and sponges all require regular filter-feeding for survival, with Nannochloropsis providing ideal nutrition supporting crown regeneration, tube construction, and long-term survival.

Copepod Culture & Live Food Production: Marine copepods represent the most important live food for reef aquariums, and Nannochloropsis serves as foundational nutrition for all commonly cultured species:

• Tigriopus californicus: Hardiest species, thrives 15-45 ppt salinity, 10-35°C, achieving exceptional reproduction on Nannochloropsis
• Tisbe biminiensis: Smaller harpacticoid, rapid reproduction, ideal for mandarins and small fish
• Apocyclops panamensis: Euryhaline paracyclopoid, tolerates freshwater to marine salinity
• Parvocalanus crassirostris: Pelagic calanoid remaining suspended in water column
• Pseudodiaptomus pelagicus: Larger calanoid for commercial aquaculture applications
• Acartia tonsa: Classic marine calanoid widely used in fish hatcheries worldwide

The EPA-rich profile transfers efficiently to copepod tissues, producing nutritionally superior copepods. The high protein content (35-50% dry weight) supports rapid development, frequent egg production, and large clutch sizes. Copepods fed Nannochloropsis develop green coloration in digestive tracts indicating active feeding.

Rotifer Enrichment & Aquaculture Feed: Marine rotifers (Brachionus plicatilis L-type, Brachionus rotundiformis S-type) serve as essential live food for marine fish larvae. Nannochloropsis provides excellent EPA-enrichment, revolutionizing marine larviculture in the 1980s. Enriching rotifers with Nannochloropsis for 4-24 hours before feeding to fish larvae transfers EPA from phytoplankton to rotifers to fish, dramatically improving larval survival rates, reducing skeletal deformities, and supporting proper neural and visual system development.

Commercial hatcheries producing grouper, snapper, sea bass, sea bream, pompano, cobia, and mahi-mahi rely heavily on Nannochloropsis-enriched rotifers for first-feeding larvae.

Culture Parameters

Optimal Growth Conditions:

• Salinity Range: 20-35 ppt optimal (tolerates 12-40 ppt)
• Temperature: 20-30°C optimal, best at 25°C (68-86°F)
• pH Range: 7.5-9.0, optimal 8.0-8.5
• Light Intensity: 100-200 μmol photons m⁻² s⁻¹
• Photoperiod: 16:8 or 24:0 light:dark hours
• Growth Rate: Doubling time 12-24 hours under optimal conditions

Culture Medium & Fertilization: Requires marine aquaculture fertilizers containing nitrogen (nitrate 500-1500 μM, ammonium, or urea), phosphorus (phosphate 30-100 μM), trace metals (iron, manganese, zinc, copper, molybdenum, cobalt), and vitamins (B12, thiamine, biotin). Standard media include F/2 medium, Guillard's medium, or commercial phytoplankton fertilizers. CO2 supplementation dramatically enhances growth rates while maintaining optimal pH.

Benefits in Reef Aquariums

Enhanced Coral Coloration: High pigment content provides carotenoids and chlorophyll potentially enhancing coral fluorescent proteins and natural coloration, particularly in SPS corals showing enhanced blue, purple, and green fluorescence.

Improved Water Quality: Live cultures actively remove nitrate, phosphate, and ammonium through biological uptake, converting dissolved nutrients into phytoplankton biomass consumed by corals and filter feeders, contributing to natural nutrient export.

Natural Food Web Support: Establishes marine food chain foundation, supporting beneficial copepods, amphipods, mysids, and ostracods contributing to ecosystem stability. Fish display better coloration, natural behaviors, improved immune function, and higher survival rates.

Commercial Aquaculture Applications

Marine Fish Hatchery Production: Essential for producing grouper, snapper, sea bass, sea bream, pompano, cobia, mahi-mahi, barramundi, and yellowtail. Used to enrich rotifers and for "green water technique" in larval tanks providing multiple benefits including rotifer nutrition, preferred light conditions, direct larval nutrition, ammonia removal, water chemistry stabilization, and oxygen production.

Shellfish Aquaculture: Critical for oyster (Pacific, Eastern, European flat), clam (Manila, hard, geoduck), scallop (bay, sea), and mussel (blue, Mediterranean, green-lipped) hatcheries. Bivalve larvae require continuous phytoplankton from straight-hinge stage through setting and metamorphosis.

Sea Cucumber & Shrimp Farming: Used for juvenile sea cucumber nutrition (Apostichopus japonicus, Holothuria scabra) and shrimp larviculture (Penaeus vannamei, monodon, japonicus).

Omega-3 Supplement Production: Industrial-scale cultivation for extracting EPA-rich oils for vegetarian/vegan omega-3 supplements and aquafeed additives replacing fish oil.