Tigriopus sirindhornae - Rare Thai Tide Pool Copepod for Premium Aquaculture

Scientific Classification & Taxonomy

Kingdom: Animalia | Phylum: Arthropoda | Subphylum: Crustacea | Class: Maxillopoda | Subclass: Copepoda | Order: Harpacticoida | Family: Harpacticidae | Genus: Tigriopus | Species: T. sirindhornae

Complete Tigriopus sirindhornae Species Profile for Marine Aquaculture

Tigriopus sirindhornae represents a rare and recently described species of harpacticoid copepod endemic to rocky intertidal tide pools along the coast of Thailand in the Gulf of Thailand. This species was scientifically described in 2004 and named in honor of Her Royal Highness Princess Maha Chakri Sirindhorn of Thailand for her dedication to science and education. The species epithet "sirindhornae" commemorates this royal patronage of scientific research.

As a member of the Tigriopus genus, T. sirindhornae shares many characteristics with the widely-cultured Tigriopus californicus including extreme environmental tolerance, benthic lifestyle, and exceptional hardiness. However, T. sirindhornae represents a distinct species adapted to tropical Southeast Asian conditions rather than the temperate Pacific coast environments where T. californicus thrives. This tropical adaptation makes T. sirindhornae particularly valuable for warm-water aquaculture applications and tropical reef aquariums maintained at 24-28°C.

Adult Tigriopus sirindhornae measure 0.8-1.3 millimeters in body length, with females (1.0-1.3mm) larger than males (0.8-1.1mm). The size range closely matches T. californicus (0.8-1.2mm), providing similar prey size suitability for reef fish, mandarin dragonets, and marine fish larvae. The moderate size fills the critical gap between small copepods like Tisbe (0.5-0.9mm) and larger species, offering versatility across diverse feeding applications.

Body coloration in T. sirindhornae typically ranges from orange-red to deep brick-red similar to T. californicus, caused by high concentrations of carotenoid pigments particularly astaxanthin accumulated from algae-based diets. Well-fed T. sirindhornae display intense red-orange coloration making them highly visible and attractive to reef fish, triggering strong feeding responses. Some individuals show slight color variation with more orange versus red tones depending on diet composition and individual genetics, though all maintain the characteristic bright coloration distinguishing Tigriopus from pale or transparent copepod species.

The body structure is typical of harpacticoid copepods - relatively robust and cylindrical with clear segmentation. The cephalothorax comprises the anterior portion, followed by narrow abdomen and distinctive forked tail rami. Females carry paired egg sacs attached laterally to genital segment, with each sac containing 20-70 eggs depending on female size, age, and nutritional status. These conspicuous dark egg sacs make gravid females easily identifiable, and the bright body coloration combined with visible egg sacs creates striking appearance in cultures and aquariums.

Tropical Adaptation and Environmental Tolerance

Exceptional Tropical Hardiness: Tigriopus sirindhornae demonstrates remarkable environmental tolerance characteristic of the Tigriopus genus, but with tropical temperature adaptation distinguishing it from temperate T. californicus. The species evolved in rocky intertidal tide pools along Thai coasts experiencing extreme environmental fluctuations including dramatic temperature swings, variable salinity from tropical rainfall and evaporation, intense solar radiation, and fluctuating oxygen levels. This harsh selective environment produced exceptionally hardy copepods tolerating conditions that would stress or kill most marine organisms.

Extreme Salinity Tolerance (Euryhaline): Like other Tigriopus species, T. sirindhornae tolerates salinities from 15-80 ppt (parts per thousand), far exceeding most marine organisms. Tide pools experience salinity extremes - torrential tropical monsoon rains can dilute salinity to 15-20 ppt within hours, while intense tropical sun and heat can evaporate water raising salinity to 50-80 ppt or higher in shallow pools. This extraordinary euryhaline capacity makes T. sirindhornae suitable for culture at various salinities:

• Standard Marine: 30-35 ppt matching typical reef aquarium salinity
• Reduced Salinity: 25-30 ppt for cost savings in commercial operations
• Brackish Water: 20-25 ppt for euryhaline tropical species applications
• Hypersaline: Tolerates temporary exposure to 50-60 ppt during culture mishaps or water quality issues

Tropical Temperature Tolerance: T. sirindhornae demonstrates temperature tolerance adapted to tropical conditions, distinguishing it from cold-tolerant T. californicus:

• Optimal Range: 24-30°C (75-86°F) - maximum reproduction and fastest development
• Acceptable Range: 22-32°C (72-90°F) - good reproduction and population growth
• Survival Range: 18-35°C (64-95°F) - survival possible but reproduction declines outside optimal range

The warm temperature requirement makes T. sirindhornae ideal for tropical reef aquariums typically maintained at 24-27°C and warm-water fish hatcheries producing tropical species. Unlike T. californicus thriving at cooler 15-22°C, T. sirindhornae struggles at temperatures below 20°C, making it specifically adapted for tropical applications.

Thai tide pools experience extreme temperature fluctuations - nighttime temperatures may drop to 22-24°C, while intense midday tropical sun can heat shallow pools to 35-38°C or higher. This thermal extremes tolerance means cultured T. sirindhornae handles temperature fluctuations common in aquaculture operations without stress or mortality, though stable temperatures within optimal range maximize reproduction.

Oxygen Tolerance: Tolerates low oxygen conditions better than most marine copepods, surviving oxygen concentrations down to 2-3 mg/L compared to optimal levels of 6-8 mg/L. Tide pools experience hypoxia overnight when photosynthesis ceases and respiration depletes oxygen. This tolerance means T. sirindhornae cultures tolerate less intensive aeration than sensitive calanoid copepods, and populations survive brief equipment failures or power outages without catastrophic losses.

pH Tolerance: Tolerates pH ranges from 7.0-9.5, though optimal reproduction occurs at pH 8.0-8.5 matching typical seawater. Tide pools experience pH swings from acidification (respiration, decomposition during warm nights) to extreme alkalinity (intense photosynthesis during day removing CO2). This tolerance provides buffer against pH fluctuations in cultures or reef aquariums.

Ammonia and Nitrite Tolerance: Demonstrates higher tolerance to ammonia and nitrite than sensitive calanoid copepods like Acartia or Parvocalanus, surviving elevated levels temporarily. While not recommended to maintain copepods in poor water quality, this tolerance means T. sirindhornae populations survive temporary water quality issues, overfeeding events, or equipment failures that might eliminate more sensitive species.

Life Cycle and Reproduction

Egg Stage: Female Tigriopus sirindhornae produce paired egg sacs containing 20-70 eggs each, depending on female size and nutrition. Well-fed mature females in optimal conditions (26-28°C, abundant food) produce 40-60 eggs per clutch. Eggs develop within sacs attached to female's genital segment, receiving no parental care beyond being carried. Egg development requires:

• 24°C: 4-5 days to hatching
• 26°C: 3-4 days to hatching
• 28°C: 2.5-3.5 days to hatching
• 30°C: 2-3 days to hatching

The faster development at warm temperatures compared to temperate T. californicus (3-7 days at 15-25°C) reflects tropical adaptation. Eggs appear orange to dark brown within sacs due to accumulated carotenoids and yolk reserves.

Nauplius Stages: Six naupliar stages (N1-N6) complete development. Nauplii hatch at 80-120 micrometers, appearing as tiny comma-shaped organisms. Total naupliar development:

• 24°C: 7-10 days
• 26°C: 6-8 days
• 28°C: 5-7 days
• 30°C: 4-6 days

Nauplii feed on phytoplankton (Nannochloropsis, Tetraselmis, Isochrysis), bacteria, and dissolved organic matter, growing progressively larger with each molt. Exhibit positive phototaxis facilitating visual predation by larval fish.

Copepodid Stages: Five copepodid stages (C1-C5) complete before adulthood:

• 24°C: 12-16 days
• 26°C: 10-14 days
• 28°C: 9-12 days
• 30°C: 7-10 days

Copepodids develop characteristic orange-red coloration and full appendage complement. Sex differentiation apparent at C4-C5 stages.

Adult Stage: Sexual maturity reached:

• 24°C: 23-31 days post-hatching
• 26°C: 19-26 days post-hatching
• 28°C: 16-22 days post-hatching
• 30°C: 13-19 days post-hatching

Females begin producing egg sacs 3-5 days after final molt, producing new sacs every 5-9 days throughout reproductive life. Shorter intervals at warmer temperatures drive faster population growth compared to temperate species.

Adult longevity:

• 24°C: 3-5 months, producing 10-20 clutches
• 26°C: 2.5-4 months, producing 8-16 clutches
• 28°C: 2-3.5 months, producing 7-14 clutches
• 30°C: 1.5-3 months, producing 6-12 clutches

Total lifetime fecundity: 240-1400 offspring per female under optimal conditions. Population doubling time 12-20 days at tropical temperatures (26-28°C), faster than temperate T. californicus (15-25 days at 20-22°C) but slightly slower than fast-reproducing Tisbe biminiensis (10-15 days).

Nutritional Composition and Value

Exceptional Protein Content: Tigriopus sirindhornae contains 48-60% protein on dry weight basis, among the highest protein contents documented in marine copepods. This exceptional protein density rivals or exceeds T. californicus (48-58%) and other harpacticoid species. Complete amino acid profile includes all essential amino acids required by marine fish including leucine, lysine, arginine, valine, threonine, methionine, histidine, tryptophan, isoleucine, and phenylalanine in proportions optimal for fish protein synthesis.

Astaxanthin and Carotenoid Pigments: The brilliant orange-red coloration results from high astaxanthin concentrations (1.0-3.0% dry weight), a powerful carotenoid pigment that transfers to fish consuming T. sirindhornae. Astaxanthin enhances fish coloration particularly in species displaying red, orange, pink, or yellow pigmentation common in tropical reef fish including anthias, basslets, certain wrasses, dottybacks, and cardinalfish. The pigment also provides antioxidant benefits supporting immune function and stress resistance. Also accumulates zeaxanthin, lutein, beta-carotene, and other carotenoids contributing to nutritional value.

Essential Fatty Acids: When fed quality phytoplankton diets, T. sirindhornae accumulates EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) omega-3 fatty acids:

• EPA: 10-20% of total fatty acids (Nannochloropsis, Chaetoceros, Tetraselmis diets)
• DHA: 6-14% of total fatty acids (Isochrysis, Tisochrysis, Pavlova diets)
• Total Omega-3: 25-40% of total fatty acids with balanced phytoplankton diet

While EPA/DHA levels are moderate compared to calanoid copepods like Acartia (35-55% omega-3) or Parvocalanus, T. sirindhornae provides adequate essential fatty acids for reef fish nutrition, particularly when cultured on mixed phytoplankton diets including both EPA-rich (Nannochloropsis) and DHA-rich (Tisochrysis, Pavlova) species.

High Digestibility: Soft exoskeleton and moderate body size make T. sirindhornae highly digestible with nutrient absorption rates of 80-92% documented in digestibility studies. High digestibility maximizes nutritional transfer and minimizes waste production in reef aquariums and culture systems.

Ideal Size Range: Adult T. sirindhornae (0.8-1.3mm) suit fish with mouth sizes 2-10 millimeters including most gobies, wrasses, dartfish, firefish, small dottybacks, juvenile angelfish, small anthias, and countless reef fish species. Copepodid stages (0.3-0.8mm) suit very small fish and settling larvae. Nauplii (0.08-0.12mm) feed smallest larvae and finicky nano species.

Tropical Reef Aquarium Applications

Mandarin Dragonet Essential Food: Mandarinfish (Synchiropus splendidus) and scooter blennies (Synchiropus ocellatus) maintained in tropical reef aquariums (24-27°C) thrive on T. sirindhornae populations. The tropical temperature adaptation makes T. sirindhornae superior to temperate T. californicus for tropical reef systems where mandarin dragonets are commonly kept. The benthic lifestyle, bright coloration, appropriate size, fast reproduction, and high nutrition make T. sirindhornae ideal mandarin food:

1. Temperature Match: Optimal 24-30°C perfectly matches tropical reef aquarium temperatures where mandarins thrive
2. Benthic Lifestyle: Colonizes all tank surfaces where mandarins hunt continuously
3. High Visibility: Intense orange-red coloration makes copepods easy for mandarins to locate
4. Appropriate Size: 0.8-1.3mm matches mandarin mouth dimensions
5. Fast Reproduction: Tropical reproduction rates replenish populations supporting continuous grazing
6. Superior Nutrition: Exceptional protein and astaxanthin enhance mandarin health and coloration

Tropical Anthias and Planktivore Nutrition: Tropical anthias species (Pseudanthias squamipinnis, P. tuka, P. evansi, P. huchtii, P. pleurotaenia) commonly maintained in reef aquariums benefit from T. sirindhornae supplementation. While primarily planktivorous, anthias opportunistically consume benthic copepods including Tigriopus colonizing rocks and equipment. The bright coloration triggers feeding responses, and the high protein/astaxanthin content enhances the spectacular coloration anthias species display.

Fairy wrasses (Cirrhilabrus species), flasher wrasses (Paracheilinus species), and other active planktivores also consume T. sirindhornae readily when copepods swim near surfaces or enter water column.

Tropical Nano Reef Aquariums: Small tropical reef aquariums (5-30 gallons) maintained at 24-27°C stocked with nano fish species benefit tremendously from T. sirindhornae populations. The tropical temperature adaptation ensures copepods thrive at temperatures optimal for nano reef inhabitants. Small gobies (Trimma species at upper temperature tolerance, Elacatinus species, small Gobiodon species), small wrasses, juvenile fish, and other nano species all consume T. sirindhornae successfully.

Tropical Marine Fish Breeding: Breeding programs for tropical clownfish (Amphiprion species), tropical dottybacks (Pseudochromis species), tropical gobies, tropical cardinalfish, and other warm-water species benefit from T. sirindhornae as supplemental larval food and adult conditioning food. The tropical adaptation ensures copepods maintain peak nutritional quality at temperatures optimal for tropical species reproduction.

Coral Reef Tank Benefits: While primarily benefiting fish, corals in systems with established T. sirindhornae populations may receive incidental nutrition when copepods contact polyps and are captured. The copepod grazing on diatoms, detritus, and biofilm also benefits overall reef ecosystem health by contributing to biological cleaning and nutrient cycling.

Culture Requirements and Methods

Optimal Culture Conditions:

• Salinity: 25-35 ppt optimal (tolerates 15-80 ppt)
• Temperature: 26-28°C optimal for maximum reproduction (79-82°F), tolerates 18-35°C
• pH: 8.0-8.5 optimal (tolerates 7.0-9.5)
• Ammonia/Nitrite: Should be undetectable; tolerates brief elevation better than calanoids
• Nitrate: <50 mg/L preferred, tolerates higher temporarily
• Dissolved Oxygen: >5 mg/L preferred, tolerates brief drops to 2-3 mg/L
• Light: Low to moderate; not light-sensitive
• Container: Any non-toxic container (glass, plastic, acrylic)

Feeding Tigriopus sirindhornae Cultures: Feed primarily on phytoplankton, also consuming bacteria, yeast, detritus, and microalgae biofilms:

Primary Diet - Live Phytoplankton:

• Nannochloropsis oculata: Ideal staple diet providing EPA, high protein, appropriate size
• Tetraselmis chui: Excellent for large adults and egg production, high protein (40-52%)
• Isochrysis galbana/Tisochrysis lutea: DHA enrichment for optimal nutritional quality
• Rhodomonas salina: Premium protein source (45-55%) for maximum reproduction
• Chaetoceros calcitrans: Diatom option providing EPA and silica

Mixed Diet Strategy: 60% Nannochloropsis + 25% Tetraselmis + 15% Isochrysis/Tisochrysis for balanced nutrition. Maintain light green water tint (100,000-500,000 cells/ml). Feed 2-3 times weekly or daily in intensive production systems.

Supplemental Foods:

• Reef-Roids or coral foods: 1-2 times weekly in small amounts
• Spirulina powder: Tiny pinch 1-2 times weekly
• Golden Pearls larval diet: 5-50 micron sizes
• Biofilm on surfaces: Copepods graze naturally-occurring biofilm

Avoid Overfeeding: Excess food decomposes causing water quality crashes.

Culture Maintenance: Container Setup:

• 1-20 liter containers depending on scale
• No substrate required, though some aquarists add live rock rubble or PVC providing surface area
• Gentle aeration beneficial but not essential (tolerates lower oxygen)
• Moderate indirect lighting or room light sufficient
• Temperature control via aquarium heater maintaining 26-28°C
• Cover containers preventing escape and contamination

Water Changes:

• 25-50% weekly removing metabolic wastes
• Match salinity and temperature to culture minimizing stress
• Siphon bottom detritus during changes

Harvesting:

• Harvest 10-30% of population weekly sustainable
• Use fine mesh net, turkey baster, or siphon collecting copepods
• Harvest adults preferentially, leaving juveniles to grow
• Rinse copepods briefly in clean saltwater before aquarium addition

Population Density:

• Maintain 50-500 copepods per liter depending on feeding intensity
• Higher densities (500-2000/L) possible with excellent water quality and heavy feeding
• Monitor for population crashes from overfeeding, ammonia spikes, or oxygen depletion

Seeding Reef Aquariums: Add 1000-5000 T. sirindhornae to established tropical reef aquariums (50-200 gallons) initiating populations. Copepods colonize live rock, substrate, glass, equipment surfaces. Populations establish over 4-8 weeks, reaching equilibrium based on food availability (phytoplankton, biofilm, detritus) and predation pressure (fish). Supplement populations every 2-4 months if heavy predation depletes numbers.

For aquariums with mandarin dragonets or heavy copepod-feeding fish, establish separate copepod refugium (sump section, hang-on refugium) protected from predation, continuously seeding display tank with production.

Advantages Over Other Copepod Species

Tropical Adaptation: Unlike temperate T. californicus optimal at 15-22°C, T. sirindhornae thrives at tropical temperatures (24-30°C) matching tropical reef aquariums and warm-water aquaculture operations perfectly. This temperature match ensures copepods maintain peak condition, maximum reproduction, and optimal nutritional quality at temperatures where tropical fish and invertebrates thrive.

Unmatched Tropical Hardiness: Combines Tigriopus genus hardiness with tropical adaptation - extreme salinity tolerance, wide temperature tolerance (18-35°C), high ammonia/nitrite tolerance, low oxygen tolerance. Makes T. sirindhornae most forgiving tropical copepod species for beginners and challenging culture conditions.

Easy Culture: Simple requirements, tolerates suboptimal conditions, reproduces reliably without specialized equipment. Easier culture than sensitive calanoid copepods (Acartia, Parvocalanus, Pseudodiaptomus).

High Visibility: Bright orange-red coloration triggers strong fish feeding responses and makes copepods easy to observe in cultures and aquariums, allowing monitoring of population health and abundance.

Benthic Lifestyle: Colonizes all surfaces providing constant food availability for benthic-feeding fish like mandarin dragonets, bottom-dwelling gobies, and substrate-foraging wrasses.

Fast Tropical Reproduction: Generation time 13-31 days (depending on temperature) allows rapid population growth. Faster reproduction at warm temperatures compared to temperate T. californicus at equivalent thermal optima.

Rare and Unique: Endemic Thai species providing unique genetic diversity and novelty for advanced aquarists and copepod collectors. Represents conservation value maintaining captive populations of rare endemic species.

Commercial Availability: While less common than T. californicus, T. sirindhornae availability increasing through specialized suppliers like PodDrop maintaining pure cultures.

Considerations and Limitations

Tropical Requirement: Requires warm 24-30°C optimal temperatures, struggling below 20°C. Not suitable for temperate aquariums or cold-water applications where T. californicus excels.

Limited Research: Less extensively studied than T. californicus or Acartia tonsa. Culture protocols, nutritional analyses, and biological data more limited requiring adaptation of protocols from related species.

Conservation Status: Endemic to Thailand with limited natural distribution. While not currently threatened, maintaining captive populations has conservation value preserving genetic diversity of this rare species.

Availability: Less readily available commercially than widespread T. californicus. Requires sourcing from specialized suppliers maintaining pure cultures.