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Blue leg Poso shrimp

Caridina caerulea

An endemic jewel from Lake Poso, Sulawesi: grey-white body with electric blue legs — one of the most fascinating shrimp in the world. Ancient lake species — requires warm, alkaline, and stable water: the opposite of classic Caridina. The 'easiest' among Sulawesi shrimp, but still reserved for experts. Mature tank 3+ months with abundant biofilm. Vulnerable species in the wild — prefer captive-bred specimens. Extremely sensitive to fluctuations and copper.

Taxonomy
Class:Malacostraca
Order:Decapoda
Family:Atyidae
Genus:Caridina
Species:Caridina caerulea

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Water Temperature

26 - 29 °C

pH Value

7.5 - 8.5

Water type

Freshwater

Invertebrate type

Freshwater shrimp

Adult size

2.5 cm

Minimum group

>= 6

GH

4 - 10 dGH

KH

5 - 7 dKH

TDS

110 - 220 ppm

Ecological role

Scavenger

Copper sensitivity

High

Species description

Geographical Origin and Habitat: Endemic exclusively to the pristine, ancient, and highly isolated tectonic Lake Poso and its immediate tributaries in Central Sulawesi, Indonesia. Caridina caerulea (universally celebrated as the Blue Leg Poso Shrimp) natively colonizes the hard, rocky, and heavily structured littoral (shoreline) zones of this massive, incredibly deep lake. These specific micro-habitats are completely characterized by massive, jagged limestone boulders, large beds of crushed rock, specific endemic aquatic sponges, and completely crystal-clear, intensely warm, heavily alkaline water with virtually zero submerged vegetation.
Taxonomy: Scientifically classified within the Atyidae family, it is a spectacular, biologically fascinating, and highly specialized Sulawesi dwarf shrimp. Morphologically, fully mature adults reach a maximum of roughly 2.0 to 2.5 centimeters (0.8-1.0 inches) in length. It possesses a delicate, deeply compact, and laterally compressed body typical of Sulawesi species. Its absolute defining, evolutionary signature anatomical features are its exceptionally elongated, spindly front walking legs used for meticulous picking, and its significantly longer rostrum (beak) compared to standard Neocaridina species.
Social Behavior: They are highly intelligent, entirely non-aggressive, but profoundly shy and deeply timid benthic invertebrates. They are completely harmless and absolutely MUST be kept in a sizable colony (absolute minimum 15-20 individuals) to establish critical security; kept in small numbers, they will permanently hide and slowly stress to death. In the aquarium, they possess a fascinating, slow, and highly deliberate scavenging lifestyle. They will spend their entire day meticulously picking microscopic biofilm and diatoms off hard surfaces, specifically remaining close to complex rock crevices for immediate retreat.
Coloration and Sexual Dimorphism: Sexual dimorphism is extremely subtle and intensely difficult to discern until fully mature; mature females possess a very slightly deeper, more rounded abdomen (pleopods) for carrying eggs, but they do NOT display the prominent "saddle" typical of other dwarf shrimp. The coloration of the Blue Leg Poso Shrimp is breathtaking, delicate, and completely unmistakable. The main body is highly translucent, glowing with a soft, pale, crystalline pinkish-orange or amber hue. The absolute highlight is its spectacular, deeply saturated, glowing neon-blue front walking legs (chelipeds) and antennae.

Care, breeding and tankmates

Tank Setup: The aquarium architecture MUST flawlessly, unconditionally, and perfectly replicate the ancient, rocky, alkaline environment of Lake Poso. A minimum 40-liter (10-gallon) tank is required for a dedicated colony. The absolute most critical requirement is hardscape: massive piles of porous, inert, or limestone-based rocks (like Dragon Stone or Seiryu Stone) to provide thousands of tight crevices and massive surface area for biofilm. Aquatic plants are not required, but floating plants can help diffuse light. Active buffering soils MUST NEVER be used; an inert, fine sandy or crushed coral substrate is mandatory.
Diet and Feeding: They are highly specialized, continuous scavengers that feed exclusively by meticulously picking microscopic biofilm, diatoms (brown algae), and specialized bacterial mats off hard, rocky surfaces. In the aquarium, they are notoriously difficult to feed because they frequently ignore commercial food. The tank MUST be highly mature (running for months) with visible algae and biofilm before introduction. To supplement, they strictly MUST be fed a highly specialized micro-diet: powdered spirulina, bacter-AE, and very high-quality sinking shrimp pellets that dissolve into fine powder.
Water Quality: Originating from the ancient tectonic Lake Poso, they are incredibly delicate and possess extreme, uncompromising water requirements. They strictly demand intensely warm tropical heat (27-30°C / 81-86°F); cooler water will kill them. Crucially, they require moderately hard water (GH 6-10) and an intensely alkaline, high pH (7.8 - 8.5) specifically requiring specialized Sulawesi mineral salts reconstituted in pure RO/DI water. They possess absolute zero tolerance for dissolved organic waste, Ammonia, or Nitrites; rigorous weekly water changes using perfectly matched RO water are unconditionally mandatory.
Compatibility and Tankmates: Compatibility is strictly limited by their extreme water parameter requirements, microscopic size, and profound, intense timidity. They are the perfect, spectacular centerpiece for a dedicated, single-species Sulawesi biotope. They MUST NEVER be housed with any fish; even the smallest, most peaceful micro-fish will utterly terrify them, causing them to hide constantly and eventually starve. They should strictly be housed alone, or potentially with specialized Sulawesi snails (like Tylomelania species) that thrive in the exact same extreme, high-temperature, highly alkaline conditions.
Aquarium Breeding: Breeding is possible but highly challenging, requiring absolute perfection in their extreme water parameters. They are direct developers; they do NOT have a larval stage. Triggered by highly stable, hot, alkaline water and abundant powdered food, mature females will carry 15-25 relatively large eggs under their abdomen for roughly 3-4 weeks. When they hatch, the babies emerge as microscopic, fully formed replicas of the adults. The babies are profoundly delicate and require a highly mature tank completely covered in complex biofilm and diatoms to survive their first critical weeks.
Risks and Diseases: The absolute greatest physical risk is rapid, lethal toxicity; they possess absolute zero tolerance for Copper, heavy metals, or tap water impurities. The use of pure RO/DI water remineralized with specific Sulawesi salts is unconditionally mandatory. The second major risk is lethal physiological collapse caused by incorrect parameters; keeping them in standard soft, acidic shrimp water or temperatures below 26°C will rapidly kill the entire colony. Finally, they will easily starve to death in newly established, sterile tanks lacking massive amounts of natural biofilm and diatoms.

Geographic Origin and Distribution

Endemic exclusively to the pristine, ancient, and highly isolated tectonic Lake Poso and its immediate tributaries in Central Sulawesi, Indonesia. Caridina caerulea (universally celebrated as the Blue Leg Poso Shrimp) natively colonizes the hard, rocky, and heavily structured littoral (shoreline) zones of this massive, incredibly deep lake. These specific micro-habitats are completely characterized by massive, jagged limestone boulders, large beds of crushed rock, specific endemic aquatic sponges, and completely crystal-clear, intensely warm, heavily alkaline water with virtually zero submerged vegetation.

Origin

North AmericaSouth and Southeast AsiaEast Asia

Invertebrate profile

Diet
Biofilm grazer
The diet of Caridina caerulea typically reflects its natural foraging behavior as a Sulawesi freshwater shrimp. It thrives on a varied diet that can include specialized commercial foods, naturally occurring biofilm, and appropriately sized organic matter. Providing a balanced nutritional profile ensures robust health, strong coloration, and proper energy levels. Supplemental feeding should be adjusted based on the maturity of the tank and the presence of natural food sources.
Ecological role
Scavenger
In its native habitat and the home aquarium, Caridina caerulea plays a vital ecological role. It contributes significantly to the processing of organic waste and the maintenance of a balanced micro-ecosystem. By engaging in natural behaviors like scavenging, grazing, or sifting, it helps prevent the accumulation of detritus. This species is often considered a crucial component of a comprehensive clean-up crew.
Shock sensitivity
Extreme
Sudden shifts in water parameters can trigger severe osmotic shock in Caridina caerulea. It requires slow, careful acclimation, preferably using the drip method over several hours. Rapid changes in temperature, salinity, or pH can lead to immediate stress, failed molts, or mortality. Maintaining absolute stability in the tank is more important than chasing specific target values.
Calcium and minerals
High
Adequate calcium levels are absolutely essential for the structural integrity and growth of Caridina caerulea. For crustaceans and snails, it facilitates proper shell and exoskeleton development, while for corals, it builds the skeletal structure. Aquarists must regularly monitor calcium concentration alongside alkalinity and magnesium. Supplementation through specialized products or mineral-rich foods may be necessary in depleted systems.
Molting
Yes
If applicable to this species, the molting process is a highly vulnerable period for Caridina caerulea. During this time, the animal will hide while its new exoskeleton hardens, requiring peace and stable water chemistry. The discarded molt should generally be left in the tank, as it provides a valuable source of recycled minerals. A lack of iodine or calcium can lead to fatal molting issues, often referred to as the 'white ring of death'.
Reproduction
Oviparous
The reproductive strategy of Caridina caerulea can range from simple cloning and fragmentation to complex larval stages requiring varying water conditions. Successful captive breeding often signifies excellent water quality and a well-balanced environment. While some species will readily multiply and populate the tank, others may require specialized rearing setups for the offspring to survive. Researching their specific larval development phase is critical for aquarists aiming to breed them.
Compatibility & tankmates
Species only
When selecting tank mates for Caridina caerulea, cautious planning is imperative to avoid predation or aggressive competition. Small or peaceful invertebrates should not be housed with aggressive fish, loaches, or large crabs that might view them as food. Conversely, some specialized invertebrates form symbiotic relationships that can be highlighted in a community setup. A heavily planted or intricately rock-scaped tank often provides necessary refuges.

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.

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Last updated: 06/30/2026