Chaetoceros calcitrans - Essential Diatom for Marine Larviculture

Scientific Classification

Kingdom: Chromista | Phylum: Bacillariophyta | Class: Mediophyceae | Order: Chaetocerotales | Family: Chaetocerotaceae | Genus: Chaetoceros | Species: C. calcitrans

Chaetoceros calcitrans Species Profile

Chaetoceros calcitrans represents a critical diatom species measuring 3-7 micrometers in diameter, featuring distinctive silica cell walls (frustules) and bristle-like setae extending from cell surfaces. This marine diatom forms chains of cells connected by setae, creating characteristic morphology easily identified under microscopy. Chaetoceros ranks among the most important phytoplankton species in commercial marine aquaculture worldwide.

The genus name "Chaetoceros" derives from Greek "chaite" (hair) and "keras" (horn), referring to the distinctive horn-like setae projecting from cells. These setae contain no cytoplasm and serve structural functions helping cells maintain position in water column and potentially deterring some grazers. In culture, Chaetoceros chains typically contain 2-8 cells, though longer chains occur under some conditions.

Nutritional Composition

Protein Content: 35-45% dry weight with complete essential amino acid profile.

Lipid Content: 15-25% dry weight with exceptional fatty acid profile:

• EPA: 20-35% of total fatty acids - Among highest diatom EPA producers
• DHA: Present in trace amounts
• Fucoxanthin: High concentrations of this diatom carotenoid with antioxidant properties
• Silica: Significant frustule silica content characteristic of diatoms

Vitamins & Minerals: Complete vitamin profile plus essential trace elements concentrated from seawater.

Commercial Aquaculture Applications

Marine Fish Hatchery Production: Chaetoceros serves as primary live food in marine finfish hatcheries producing grouper, snapper, sea bass, sea bream, pompano, cobia, and numerous commercially valuable species. The 3-7 micrometer cell size matches mouth gape of first-feeding fish larvae, while high EPA content supports proper neural development and eye formation. Optimal size and nutrition make Chaetoceros indispensable for initial larval feeding stages.

Rotifer Culture for Larviculture: Marine rotifers (Brachionus plicatilis, B. rotundiformis) achieve maximum population densities and highest nutritional quality when cultured on Chaetoceros diets. The diatom's biochemical profile transfers essential fatty acids to rotifers, which then provide complete nutrition to fish larvae. The EPA-rich profile particularly benefits rotifer egg production and nauplii quality.

Bivalve Shellfish Aquaculture: Commercial oyster farms, clam hatcheries, scallop facilities, and mussel farms rely extensively on Chaetoceros for larval bivalve nutrition. The cell size and nutritional profile support rapid larval development, high survival rates, and superior settlement success. Chaetoceros ranks among the top three phytoplankton species for shellfish aquaculture globally.

Copepod Production: Marine copepods including Acartia tonsa, Pseudodiaptomus pelagicus, and Parvocalanus crassirostris achieve exceptional reproduction when fed Chaetoceros cultures. The diatom's fatty acid profile particularly benefits copepod egg production and nauplii development.

Cultivation Protocols

Culture System Requirements:

• Salinity: 20-35 ppt, optimal 30-33 ppt
• Temperature: 20-25°C (68-77°F) optimal
• pH: 7.5-9.0, optimal 8.0-8.5
• Light: 100-200 μmol photons m⁻² s⁻¹
• Photoperiod: 24:0 or 16:8 light:dark cycles
• Silicate Requirements: ESSENTIAL for diatom frustule formation (>1-2 mg/L)
• Growth Rate: Doubling time 18-30 hours

Critical Nutrient Requirements: Chaetoceros requires silicate (sodium metasilicate, sodium silicate) in addition to standard nitrogen, phosphorus, and trace metals. Silicate concentration must be maintained above 1-2 mg/L for optimal frustule formation and cell division. Insufficient silicate causes growth cessation and cell deformities. Use F/2+Si medium or Guillard's f/2 with additional sodium silicate.

Reef Aquarium Applications

Natural Diatom Supplementation: Provides natural diatom diversity supporting established copepod populations, encouraging breeding without reliance on detritus-based nutrition.

Nutrient Cycling: Silicate uptake contributes to natural silicate cycling in reef systems, potentially reducing nuisance diatom blooms on surfaces.

Copepod Food Web Support: Regular additions maintain thriving copepod populations providing continuous live food for reef fish, particularly copepod-specialists like mandarins, anthias, and dartfish.

Considerations: Regular diatom additions introduce silicate into reef aquariums, which can potentially fuel nuisance diatom blooms on aquarium glass and substrate. This requires consideration when using diatom phytoplankton species versus flagellate species in reef systems.