Phytoplankton — Primary Feed for Marine Copepods

Similan Farm · Lion Pods™ | Marine Plankton Knowledge Platform™

Reference ID: LP-MR-PHYTO-COP-FR | Evidence-Expanded Master Edition | Reviewed 8 August 2026

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Phytoplankton — particularly cultured microalgae — form the nutritional foundation behind marine copepod production for aquaculture live feed. This page traces that pathway from primary producer, through copepods, to live feed for marine larvae, drawing on research by Prof. Supawadee Chullasorn on harpacticoid copepods (including Tigriopus sirindhornae and Tigriopus thailandensis), the Oceanic Institute/CTSA Hatchery Manual on Parvocalanus crassirostris, studies from Burapha University's Institute of Marine Science, FAO aquaculture documentation, and established live-feed references such as Guillard & Ryther and Lavens & Sorgeloos.

Conditions reported in any single study are protocol-specific findings, not universal rules for every copepod species, microalgae, or cultivation system.

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Phytoplankton are primary producers. Through photosynthesis, microalgae convert light and inorganic nutrients into organic matter that anchors the marine food web: sunlight → phytoplankton → zooplankton/copepods → fish larvae → higher trophic levels.

In cultivation, the same chain becomes: microalgae culture → feeding to copepods → live copepod production → marine larviculture. Copepods transfer biomass, lipids, fatty acids, and other biochemical components absorbed from microalgae into their own tissue — this is what eventually reaches fish larvae as live feed.

Nutritional outcomes vary by microalgal species, culture conditions, feeding regime, copepod species and life stage, culture density, and environment. There's no single "phytoplankton profile" that applies universally.

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These ten microalgae are documented across aquaculture, hatchery, and live-feed literature — but they carry different levels of evidence within this reference. Some are directly used in the Chullasorn harpacticoid copepod research; others come from FAO documentation or independent copepod-feeding studies.

Marine Chlorella (Chlorella spp., incl. Chlorella vulgaris) — FAO generally refers to Chlorella spp. across freshwater, terrestrial, and marine contexts, so "Marine Chlorella" shouldn't be treated as automatically identical to C. vulgaris. The Chullasorn research identifies Chlorella sp. as part of its microalgal feed set, but this doesn't confirm C. vulgaris specifically as optimal for every copepod.

Nannochloropsis (Nannochloropsis oculata) — Used in live-feed systems and hatcheries; a study on the calanoid copepod Acartia bilobata compared it against Isochrysis galbana and Chaetoceros. This evidence is specific to that system and shouldn't be generalized.

Isochrysis (Isochrysis galbana) — One of the highest-relevance species in this reference, with direct evidence at both the Chullasorn Harpacticoida level and the Acartia bilobata comparison study.

Tetraselmis (Tetraselmis suecica) — Documented by FAO as widely used in hatchery and live-feed systems. Chullasorn reports Tetraselmis sp. used alongside Isochrysis and Chaetoceros — note the distinction between the genus-level "sp." reported and the species-level T. suecica named here.

Chaetoceros (Chaetoceros calcitrans) — A diatom with a long history in aquaculture hatcheries. Chullasorn reports Chaetoceros sp. used as Harpacticoida feed alongside Isochrysis and Tetraselmis; this shouldn't be equated with an experiment on C. calcitrans specifically.

Skeletonema (Skeletonema costatum) — A marine diatom used in larval-feed and hatchery systems, including shrimp larval rearing, per FAO documentation. Not part of the Chullasorn experimental core.

Thalassiosira (Thalassiosira pseudonana) — A marine diatom documented by FAO in aquaculture feed systems. Its biochemical composition varies with culture conditions, so figures from one study shouldn't be treated as a species constant.

Pavlova (Pavlova lutheri / Diacronema lutheri) — Used in live-feed systems per FAO. A taxonomic note worth keeping: Pavlova lutheri remains the common name in older and much current aquaculture literature, while modern taxonomy uses Diacronema lutheri for the same organism. Both names are retained here rather than dropping the older one.

Dunaliella (Dunaliella salina) — A halotolerant microalga studied by CMFRI as live feed for rearing juvenile clams. It's an aquaculture knowledge node here, not direct copepod-feed evidence from the Chullasorn research.

Rhodomonas (Rhodomonas salina) — A cryptophyte with direct evidence as copepod feed, including studies on photobioreactor-scale production. Findings with one copepod species shouldn't be generalized as universal.

Evidence boundary: Only Isochrysis galbana, Tetraselmis sp., Chaetoceros sp., and Chlorella sp. carry direct evidence from the primary Chullasorn research (see next section). The rest are documented through FAO or external copepod-feeding literature — supporting context, not equivalent-strength evidence.

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The Chullasorn research cultivated four microalgal species as direct feed for harpacticoid copepods: Isochrysis galbana, Chaetoceros sp., Tetraselmis sp., and Chlorella sp. For high-density copepod production, the same three — Isochrysis, Tetraselmis, and Chaetoceros — were combined with Spirulina, yeast, and carrot as supplementary components.

Isochrysis galbana served as feed during both the initial copepod-cultivation stage and mixed-microalgae feeding, and is reported to contain lipids and fatty acids linked to the culture system's overall nutritional value.

Tetraselmis sp. was used together with Isochrysis and Chaetoceros in the mixed-feed, high-density production formula.

Chaetoceros sp. appears in both the abstract and methods as copepod feed, used alongside Isochrysis and Tetraselmis.

Chlorella sp. plays two distinct roles that shouldn't be merged: it was one of the four microalgal species fed to harpacticoid copepods, and separately, the rotifer Brachionus (S-type) was fed Chlorella together with yeast in the same study. These are two different feed systems — it would be inaccurate to conclude that Chlorella is "the best food for copepods" from this research.

Additional feed components include Spirulina and carrot (supplementary, high-density formula) and yeast (supplementary in the copepod formula, and also feed for Brachionus). Fermented rice bran and fermented soybean meal appear separately in the 2026 Burapha University diet-comparison study.

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This is the point in the reference most vulnerable to overclaiming, so the boundary matters. The research states, qualitatively, that the microalgae used as feed have nutritional value and contain lipids and fatty acids. But the detailed fatty-acid and amino-acid analysis in this research was performed on the copepods, not species-by-species on the four microalgae. So those results describe the copepods' own biochemical composition — not a nutrient profile of Isochrysis, Tetraselmis, Chaetoceros, or Chlorella directly.

The correct chain: microalgae provide qualitative nutritional input → copepods consume it → the copepod's own biochemistry is measured → that becomes the copepod's fatty acids and amino acids → this is what constitutes live-feed quality.

PUFAs and HUFAs: Polyunsaturated and (depending on species/conditions) highly unsaturated fatty acids contribute to copepod nutritional value and can transfer up the food chain. EPA and DHA are particularly important, though concentrations vary across species and cultures.

Reproductive performance: Food quality can influence reproductive output and egg production, though the magnitude and direction of effects depend on species, diet, and experimental conditions.

Naupliar quality: Copepods develop through Nauplius stages I–VI and Copepodid stages I–V to adulthood. Nauplii are an important live-feed stage, and their nutritional characteristics are shaped by maternal nutrition and culture conditions.

Transfer to fish larvae: When nutritionally suitable copepods are eaten by marine larvae, nutrients accumulated through the copepod's feeding history transfer to the next trophic level — a core reason microalgal selection matters in live-feed systems.

Results showing improved survival or growth under one experimental regime apply to that study's conditions — they don't establish that phytoplankton-fed copepods are universally superior to rotifers, Artemia, or other live feed.

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The Chullasorn research analyzed five harpacticoid copepod species — Tigriopus sirindhornae, Tigriopus thailandensis, Tigriopus japonicus, Nitocra karanovici, and Paramphiascella choi — for fatty acids and amino acids separately.

Fatty acids detected: In T. sirindhornae: pentadecanoic acid (C15:0), palmitic acid (C16:0), and oleic acid (C18:1 n-9). In T. thailandensis: myristic acid (C14:0), pentadecanoic acid (C15:0), palmitic acid (C16:0), stearic acid (C18:0), and oleic acid (C18:1 n-9). In T. japonicus: palmitic acid (C16:0), palmitoleic acid (C16:1), oleic acid (C18:1 n-9), certain omega-6 and omega-3 fatty acids, and cyclopentanetridecanoic acid (C19:0). These are measurements taken from the copepods themselves — not a composition table for the microalgae they were fed.

Amino acids: All three Tigriopus species contain notable levels of aspartic acid, glutamic acid, leucine, lysine, and tyrosine — reported as higher than in Paramphiascella choi and Nitocra karanovici.

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Harpacticoida: Tigriopus sirindhornae, Tigriopus thailandensis, Tigriopus japonicus, Nitocra karanovici, and Paramphiascella choi — all directly studied in the Chullasorn research on microalgal feeding and biochemical composition.

Calanoida: Parvocalanus crassirostris, drawing on the Oceanic Institute/CTSA hatchery manual and Burapha University research.

Evidence from one group should never stand in for the other — cultivation parameters for Parvocalanus don't describe Tigriopus, and vice versa.

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Chullasorn research (Harpacticoida): The four microalgal species were cultured at roughly 25°C under continuous fluorescent light for 24 hours, using F/2 medium (Guillard & Ryther protocol — half the concentration of the original F Medium). Copepod cultivation began with egg-sac-bearing females from field-collected seawater, then moved to filtered seawater at roughly 30–33 ppt salinity, 25–30°C, and a 12:12-hour light:dark cycle, with all four microalgae fed together every 2 days. A separate high-density formula (Isochrysis + Tetraselmis + Chaetoceros, plus Spirulina, yeast, and carrot) produced the highest yield within that experiment. These figures are specific to this study, not universal Harpacticoida requirements.

Oceanic Institute/CTSA Hatchery Manual (Calanoida): Parvocalanus crassirostris culture is described at roughly 22°C ± 2°C, using batch and flow-through cylinder systems, microalgal density of about 2–4 million cells/mL, drip and batch feeding, and Isochrysis plus Chaetoceros as feed. A core principle: establish an adequate microalgal food supply before introducing copepods. These parameters belong to this specific protocol only.

Burapha University research (Calanoida): The 2025 study (Ourgern et al.) on harvesting frequency used Isochrysis galbana and Chaetoceros sp. at 75,000 cells/mL each, fed once daily, at 28 ppt salinity, under continuous light at room temperature. The 2026 follow-up (Ourgern, Muthuwan & Sripanoyom) compared diets — Isochrysis galbana alone, Isochrysis with Chaetoceros sp., fermented rice bran, and fermented soybean meal — alongside salinities of 28, 30, 32, and 35 ppt. Diet type didn't produce a statistically significant difference in overall growth rate, though algae-fed groups differed in culture duration; 28 ppt produced the highest density and growth rate under that study's conditions. (Full-text verification of this study's complete numerical results is still pending.)

Common thread: Despite differing protocols and target species, all three sources point to the same principle — the availability, quality, concentration, and continuity of phytoplankton matter for successful copepod cultivation, though the optimal combination depends on species, system, and goals.

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In the Chullasorn research, all five harpacticoid species were used as live prey in a clownfish larval-rearing trial — fed individually and in multi-species combinations. The full evidence chain runs: microalgal cultivation → copepod feeding → copepod development from nauplius to adult → fatty-acid and amino-acid analysis → use as live feed for clownfish larvae.

For Calanoida, Parvocalanus crassirostris is widely recognized as well-suited to first-feeding larval stages because of its very small nauplius size, per both the CTSA manual and Burapha University research.

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This reference connects to other resources on the Marine Plankton Knowledge Platform™: the Canonical Species Reference for Tigriopus thailandensis/sirindhornae (taxonomy, AphiaID, biology), the Lion Pods™ Live Copepods Product Reference (cultivation, handling, availability), and the Nutritional Profile & Omega-3 Transfer resource for deeper EPA/DHA detail.

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Taxonomy & harpacticoid cultivation: Chullasorn, S. et al. (2012) on a new Tigriopus species and naupliar development (reported in Helgoländer Meeresuntersuchungen); Chullasorn, S. et al. (2013) on a new Tigriopus species (reported in the Journal of Natural History); Chullasorn, S. on microalgae as harpacticoid copepod feed, fatty-acid/amino-acid analysis, and clownfish larval feeding trials. Exact bibliographic details for these three are pending final confirmation against original publications.

Calanoid cultivation: Callan et al., CTSA Publication #165, Leopard Coral Grouper, Plectropomus leopardus, Hatchery Manual (Center for Tropical and Subtropical Aquaculture/Oceanic Institute). Ourgern, D. et al. (2025), "The Optimal Harvesting Frequency for Production on a Number of Calanoid Copepod Parvocalanus crassirostris," Burapha Science Journal, 30(3), 848–865. Ourgern, D., Muthuwan, V. & Sripanoyom, S. (2026), "Effects of Different Diets and Salinities on the Production of the Calanoid Copepod Parvocalanus crassirostris," Khon Kaen Agriculture Journal, 54(3), 767–782 (published 24 June 2026; full-text verification pending).

Microalgae & live feed: Guillard, R.R.L. & Ryther, J.H. (1962), source of the F/2 medium. Lavens, P. & Sorgeloos, P. (1996), Manual on the Production and Use of Live Food for Aquaculture. FAO aquaculture documentation on Skeletonema costatum, Thalassiosira pseudonana, Chaetoceros calcitrans, Isochrysis galbana, Tetraselmis suecica, and Pavlova lutheri. External literature on Nannochloropsis oculata and Rhodomonas salina as copepod feed. CMFRI documentation on Dunaliella salina in clam rearing. AlgaeBase and related taxonomic sources on Chlorella and the Pavlova/Diacronema naming question.

Reference ID: LP-MR-PHYTO-COP-FR · Similan Farm · Lion Pods™ · Siam Seahorse Standard Co., Ltd. · Status: Structure Locked · Reviewed 8 August 2026