Field observation
Direct Neocaridina evidence
Sidorovskyi, 2026. Fisheries Science of Ukraine 1(75): 98-114.
Source taxon as published: Neocaridina davidi
Study shape: Hydrobiological dip-net collections at two coordinates were preserved in 96 percent ethanol and identified by stereomicroscopy; later visits were used to report non-detection after the initial records.
Experimental unit: Field collection event at either of two Kharkiv water bodies; sampling frequency, effort and detection probability were not reported
Environment: Two urban water bodies in Kharkiv, Ukraine, surveyed between June 2020 and December 2025
Endpoints: specimen occurrence, body length, sex count, ovigerous-female count, later non-detection, site context.
What it can support: The article documents 10 and 6 shrimp at one site in 2020 and 2021, seven at a second site in 2024, ovigerous females in every positive collection and later non-detection at both sites.
What it cannot support: Later non-detection does not prove extinction because sampling effort and detectability were not reported. Identification was described as stereomicroscopy without diagnostic character results or a molecular confirmation. The end of warm runoff was not an assigned temperature treatment, and no released source stock was traced. The observations do not establish a thermal threshold, prove release causation or make any climate release-safe.
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Field observation
Direct Neocaridina evidence
Prati et al., 2025. BioInvasions Records 14(2): 403-419.
Source taxon as published: Neocaridina davidi; Ecytonucleospora hepatopenaei, Orthosomella lipae, Microsporidium sp. SRE01 and Microsporidium sp. SRE02 as named by the source
Study shape: Forty shrimp were dip-netted at each of three sites and preserved immediately in 96 percent ethanol. All were identified morphologically, measured, sexed or classified as immature, dissected, visually screened internally and tested molecularly. Host CO1 and microsporidian SSU rRNA amplicons were Sanger sequenced and placed with reference sequences in maximum-likelihood phylogenies with 1000 bootstrap replicates.
Experimental unit: Individual field-collected shrimp for morphology, internal visual screening and molecular detection; one date and three sites in two catchments for the field occurrence observations
Environment: Three freshwater sites in two catchments on La Reunion Island sampled on 15 April 2024 at 24.5 to 26.2 C and 76 to 268 microS/cm conductivity
Endpoints: host morphology and CO1 identity, sex and life-stage counts, carapace length, microsporidian PCR-positive count, sequence similarity and phylogenetic placement, site occurrence, one-day temperature and conductivity.
What it can support: Five of 120 sampled shrimp were PCR positive for four reported microsporidian sequence types: two Orthosomella lipae detections at the Salazie creek, and one Ecytonucleospora hepatopenaei, one Microsporidium sp. SRE01 and one Microsporidium sp. SRE02 detection at Bras Citronnier. None of the 40 Ravine Seche shrimp was positive. All 120 hosts shared one CO1 haplotype reported as 100 percent similar to the N. davidi reference set.
What it cannot support: This is a one-day field sample from three sites, not an aquarium or trade prevalence estimate. The paper reports no histology, tissue lesions, clinical signs, survival, experimental transmission, pathogenicity or treatment endpoint, and it did not test native co-occurring shrimp for parasites. Ethanol preservation prevented epibiont analysis. The single host CO1 haplotype cannot prove a single introduction, seller line, release event or movement route between catchments. Sequence similarity cannot establish parasite origin or that N. davidi introduced any organism. One Table 2 subgroup is internally inconsistent, listing 16 immatures while reporting two positives as 2 of 14, so subgroup percentages should not be repeated as settled denominators. The one-day site temperature and conductivity readings are not aquarium care limits, and zero of 40 at one site is not proof of absence.
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Morphology or taxonomy
Neocaridina identity evidence
Bochini et al., 2024. Boletim do Instituto de Pesca 50: e849.
Source taxon as published: One adult female identified by the source as Neocaridina davidi and deposited as voucher CCDB 6963
Study shape: Three double-bottom shrimp-boat trawls on one coastal sampling date yielded the single specimen. It was frozen, preserved in 100 percent ethanol, measured, compared with published morphology methods and sequenced at mitochondrial COI and 16S plus nuclear 18S and H3 loci. COI entered a maximum-likelihood analysis with a model selected by Bayesian information criterion and 1,000 ultrafast bootstrap replicates; the other loci were used as identity checks.
Experimental unit: One collected and vouchered adult female for morphology and all four molecular markers; one site, one date and three incompletely quantified trawls for the occurrence observation
Environment: One coastal sampling event on 14 February 2022 at Candeias beach, Pernambuco, Brazil, where three double-bottom shrimp-boat trawls recovered one live specimen among filamentous algae
Endpoints: voucher identity, carapace length, morphological identification, COI phylogenetic placement and genetic distance, 16S sequence, 18S sequence, H3 sequence.
What it can support: The source documents one vouchered adult female identified as N. davidi from a Brazilian coastal marine trawl. Its COI sequence was reported at zero genetic distance from selected Polish and Canadian N. davidi sequences, and the authors deposited reported COI, 16S and 18S sequence accessions.
What it cannot support: One animal establishes a specimen occurrence, not an established or reproducing Brazilian population. The study did not report ambient salinity, temperature, depth, capture duration, animal condition after capture, residence time, physiological measurements, osmoregulation, survival, reproduction, abundance, repeated sampling or sampling of the nearby lagoon and estuary. Diagnostic morphological character states were not tabulated, and only COI had a comparative phylogeny; identical short mitochondrial sequences cannot trace a European source, aquarium seller, release event, ancestry or route. The reported H3 identifier SUB14399993 is a submission identifier rather than a standard GenBank accession. An aquarium-trade origin was proposed as the most plausible hypothesis but was not directly tested. This record cannot establish marine tolerance, a salinity acclimation method, South American distribution, population impact, parasite transfer, a trade-line identity or permission to release aquarium animals.
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Field observation
Direct Neocaridina evidence
Prati et al., 2024. Biological Invasions 26: 2499-2523.
Source taxon as published: Neocaridina davidi
Study shape: Feral occurrence, environmental conditions and intracellular parasite relationships were investigated.
Experimental unit: Field population, site and sampled animal, depending on endpoint
Environment: European feral populations with field sampling and molecular parasite work
Endpoints: feral occurrence, range expansion, microsporidian detection, environmental context.
What it can support: Feral populations and intracellular parasite associations exist in the sampled locations.
What it cannot support: One site value is not a care boundary, and field parasite detection is not a prevalence estimate for the aquarium trade.
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Morphology or taxonomy
Neocaridina identity evidence
Shih et al., 2024. Zoological Studies 63: 18.
Source taxon as published: Eight Neocaridina species or provisional lineages from Japan
Study shape: COI DNA barcoding, morphology and geographic context were combined to identify native, non-native and provisional Neocaridina lineages.
Experimental unit: Collected specimen and locality, with sequences interpreted within the sampled phylogeny
Environment: Museum-deposited specimens from eighteen sites in Kyushu and southern Honshu
Endpoints: morphological characters, COI haplotypes, species delimitation, geographic occurrence.
What it can support: Integrative evidence distinguished several co-occurring Neocaridina lineages and exposed limits of a single barcode or character.
What it cannot support: The Japanese field result does not identify a commercial colour line, establish ancestry from a photograph or resolve every competing species treatment.
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Morphology or taxonomy
Neocaridina identity evidence
Onuki and Fuke, 2022. Conservation Genetics 23: 967-980.
Source taxon as published: Neocaridina denticulata and invasive Neocaridina davidi
Study shape: Genome-wide SNPs, mitochondrial data and morphology were combined across sites.
Experimental unit: Field-collected specimen nested within site
Environment: Nineteen field sites around Lake Biwa
Endpoints: species assignment, population structure, site occurrence.
What it can support: Native and invasive lineages can require combined genetic and morphological evidence to distinguish.
What it cannot support: Colour or a seller label cannot reproduce the identification, and occurrence does not create aquarium care limits.
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Field observation
Direct Neocaridina evidence
Schneider et al., 2022. Diseases of Aquatic Organisms 150: 125-130.
Source taxon as published: Neocaridina davidi; Enterocytozoon hepatopenaei and Microsporidium sp. EFB01 as named by the source
Study shape: Seventy-five ethanol-preserved adults were identified morphologically and screened for microsporidians by PCR from muscle tissue. Three randomly selected hosts received CO1 sequencing. Positive microsporidian amplicons were sequenced, compared with GenBank and placed in maximum-likelihood trees with 999 bootstrap replicates.
Experimental unit: Individual field-collected shrimp for PCR detection and carapace length; three randomly selected shrimp for host CO1 confirmation; one stream, one site and one sampling date for the population observation
Environment: One dip-net collection on 14 December 2021 from the Finkelbach, a German tributary of the River Erft, at 9 C, pH 7.65, dissolved oxygen 9.8 mg/L and reported conductivity 620 microS/cm
Endpoints: host identification, PCR-positive microsporidian count, sequence similarity, phylogenetic placement, sex, carapace length, visible epibiont and parasite examination.
What it can support: Four of 75 sampled shrimp were PCR positive for microsporidians. Three yielded sequences reported as 99.56 percent similar to Enterocytozoon hepatopenaei isolates, although only two were suitable for phylogenetic analysis; the fourth yielded the unresolved Microsporidium sp. EFB01 sequence. The three host CO1 sequences were 99.68 percent similar to one Taiwanese N. davidi reference.
What it cannot support: This is a one-date field detection from one German stream, not an aquarium-trade prevalence estimate or a transmission study. Only three hosts received molecular confirmation, and the paper does not report extraction blanks, PCR negative controls, product lengths, histology, tissue lesions, clinical signs, survival, transmission tests or treatment. PCR from muscle tissue cannot establish visible diagnostic characters or disease severity. The three E. hepatopenaei-positive shrimp were smaller than the 71 uninfected shrimp, but no supported inferential comparison was reported and three positives cannot establish growth suppression. Sequence similarity does not establish where either organism originated, that N. davidi introduced it, pathogenicity to native fauna, zoonotic risk or a home treatment.
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Morphology or taxonomy
Neocaridina identity evidence
Han et al., 2019. BMC Genetics 20: 86.
Source taxon as published: Four Neocaridina species or provisional lineages from Taiwan
Study shape: COI sequences, phylogeographic structure and demographic models were used to infer species boundaries and colonization histories.
Experimental unit: Collected specimen, haplotype and sampled locality depending on analysis
Environment: Four hundred seventy-nine specimens from thirty-five Taiwanese localities
Endpoints: COI lineage, haplotype structure, species delimitation, colonization-time inference.
What it can support: The sampled Taiwanese Neocaridina contained multiple geographically structured lineages with different inferred histories.
What it cannot support: Phylogeographic inference does not establish the ancestry, relatedness, purity or species of a commercial colour morph.
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Morphology or taxonomy
Direct Neocaridina evidence
Shih, Cai and Chiu, 2019. ZooKeys 817: 11-23.
Source taxon as published: Neocaridina fonticulata Shih, Cai and Chiu, 2019, described from type and additional material collected at Sheding, Kenting, southern Taiwan
Study shape: The authors described a holotype, multiple paratype lots and additional field material using external morphology and drawings, compared material of Neocaridina ikiensis, measured five eggs from each of four ovigerous females, and analyzed a 658-base-pair mitochondrial COI segment from four Sheding specimens with Bayesian and maximum-likelihood phylogenetic methods and pairwise distances.
Experimental unit: Individual deposited specimen for morphology, four source shrimp for COI that yielded one reported haplotype, and 20 eggs nested within four ovigerous females for egg measurements
Environment: A leaf-litter layer in a small, slow-flowing headwater stream beside a spring outlet on a limestone hill at Sheding, Kenting; the paper reports about 25 C water, pH 7.06 to 7.16 and dissolved oxygen 7.33 to 7.70 mg/L at the collection site, while examined specimens were preserved in 70 to 95 percent ethanol
Endpoints: type locality and deposited material, rostrum and appendage diagnostic characters, male first and second pleopod morphology, egg dimensions, live colour description, COI haplotype and phylogenetic placement, pairwise mitochondrial distance.
What it can support: The combined type material, comparative morphology and sampled COI evidence support recognizing N. fonticulata as a distinct Neocaridina species in the reviewed 2019 treatment. Diagnostic evidence includes the rostrum, pereiopods and male first and second pleopods. The four sequenced shrimp produced one 658-base-pair COI haplotype, LC427866, and the smallest reported K2P distances to sampled N. ketagalan and N. saccam were 5.42 and 5.43 percent.
What it cannot support: The species was then known only from one Sheding locality, so the report does not establish its complete distribution, population size, seasonal habitat range or conservation status; the authors prediction that it may occur in eastern Taiwan was not a sampled result. Several diagnostic characters require an adult male, dissection and specialist comparison, so body colour or one aquarium photograph cannot identify the species or distinguish it from a trade morph. The molecular result used four shrimp, one mitochondrial haplotype and no nuclear locus, cross, genomic ancestry test or blind identification validation. Mitochondrial separation in this sample does not authenticate a seller label, certify a colour line, prove reproductive isolation or identify another animal by appearance. Site temperature, pH and dissolved oxygen are locality observations without temporal replication or an assigned comparison, not aquarium optima, tolerances or care targets. Aquarium-held photographs were for observation after collection, not a husbandry experiment.
Related source material: GenBank COI accession LC427866
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Field observation
Direct Neocaridina evidence
Jablonska et al., 2018. Knowledge and Management of Aquatic Ecosystems 419: 14.
Source taxon as published: Neocaridina davidi identified by morphology and a 610-base-pair COI fragment
Study shape: Qualitative hydrobiological hand-net samples collected field shrimp in July 2003, November 2013 and June 2017. Morphology was compared with published descriptions. COI sequences from field and amateur-aquarium animals were aligned with five Taiwan and Hawaii reference sequences, assigned to haplotypes and placed in a neighbour-joining tree.
Experimental unit: Collected animal nested within three field collection events and one aquarium comparison source. Only June 2017 reports standardized effort: one square metre sampled for approximately 15 minutes. The 2003 formaldehyde-preserved sample was unavailable for COI analysis.
Environment: A roughly 4.5 km artificial canal connected to the lower River Oder near Gryfino, Poland, receiving heated Dolna Odra Power Station cooling water, with fine sand and mud substrate, partial concrete banks and submerged vegetation
Endpoints: field occurrence by year, sex and ovigerous status, body length and diagnostic morphology, 610-base-pair COI sequence, haplotype assignment, neighbour-joining placement.
What it can support: Fifteen field shrimp were found in three positive collection years spanning 2003 to 2017, including one ovigerous female in November 2013. Morphology and seven field COI accessions supported N. davidi identity. The seven field and six amateur-aquarium sequences generated by the study shared one COI haplotype, supporting close mitochondrial similarity within that comparison.
What it cannot support: The three positive years were not continuous monitoring, and qualitative sampling with mostly unreported effort cannot estimate abundance, density, occupancy, population trend or detection probability. One ovigerous female supports reproductive condition, not observed hatching, recruitment or proof that local reproduction maintained the records. The authors explicitly retained repeated yearly introductions as an alternative. The canal was artificially heated; the paper reports 27 to 29 C in June-July and 15 C in November but no winter minimum, winter sample, thermal time series or comparison site. It cannot establish cold tolerance, winter survival, a home temperature range or a 27 to 28 C breeding optimum. A shared short mitochondrial haplotype does not trace an aquarium source, seller, release event, nuclear ancestry or transfer direction. The study measured no survival, growth, water chemistry beyond temperature, ecological impact, pathogen transfer or control outcome. Failure to find a threat is not proof of no impact, and field occurrence never makes release safe.
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Field observation
Direct Neocaridina evidence
Schoolmann and Arndt, 2018. Limnologica 71: 1-7.
Source taxon as published: Neocaridina davidi
Study shape: Repeated field sampling described population structure, reproduction and dispersal.
Experimental unit: Field samples from one invaded stream system
Environment: Thermally affected German stream followed for 27 months
Endpoints: size-frequency structure, ovigerous females, population persistence, dispersal.
What it can support: A reproducing feral population persisted and dispersed under the recorded field conditions.
What it cannot support: Field estimates do not establish aquarium lifespan, a species temperature optimum or a release-safe climate.
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Controlled experiment
Direct Neocaridina evidence
Vazquez et al., 2017. Journal of Crustacean Biology 37(4): 367-373.
Source taxon as published: Neocaridina davidi
Study shape: Newly hatched shrimp were randomly assigned to 2.5, 5 or 10 animals/L for 90 days in 2 L vessels containing 5, 10 or 20 shrimp. The results table reports 8, 9 and 7 vessel replicates, respectively. A second experiment randomly assigned ten 30-day juveniles to each of five mixed-sex, five female-only and five male-only vessels at 5 animals/L.
Experimental unit: Two-litre vessel. Shrimp in each vessel were weighed together every 30 days in the density experiment, so the repeated response was vessel mean mass rather than an individually tracked trajectory. Whole-vessel biochemical homogenates were pooled across replicates when biomass was insufficient.
Environment: Two-litre culture vessels at 27 +/- 1 C with 0.7 g Java moss, continuous aeration and weekly complete water replacement
Endpoints: vessel mean wet mass through 90 days, model-estimated survival, phenotypic sex ratio, presence of ovigerous females, whole-vessel glycogen, lipid and protein concentration, mixed-sex versus monosex vessel mean mass and survival.
What it can support: Under the tested juvenile grow-out conditions, vessel mean mass diverged after day 30 and was lower at 10 animals/L than at 2.5 or 5 animals/L by days 60 and 90. Final females at 2.5 animals/L were 45 percent heavier than females at 10 animals/L, males at 2.5 animals/L were heavier than males at both higher densities, and model-estimated 90-day survival did not differ statistically among densities. Monosex versus mixed culture did not change mean mass or survival in the second experiment.
What it cannot support: This does not establish shrimp per gallon, a home-aquarium carrying capacity, a disease or welfare threshold, or a minimum starter group. The units were small juvenile grow-out vessels with daily food described as ad libitum and approximately 4 percent of vessel biomass, continuous aeration, weekly complete water replacement and removal of every new offspring. Individuals were not tracked, starting vessel counts were unequal across densities, brood and family contributions were not reported, food intake was not measured, and ovigerous presence was recorded without egg, hatch or recruitment outcomes. Survival percentages were model estimates rather than raw tank-wide guarantees. Biochemical samples sometimes pooled vessel replicates, weakening the original unit boundary. Ninety days does not represent a mixed-age, multigeneration colony or lifetime health.
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Morphology or taxonomy
Direct Neocaridina evidence
Naruse, Shokita and Cai, 2006. Proceedings of the Biological Society of Washington 119(1): 25-31.
Source taxon as published: Neocaridina iriomotensis Naruse, Shokita and Cai, 2006, described from the upper reaches of Nishifunatsuki in the Nakama River, Iriomote Island, Japan
Study shape: The listed material contains one male holotype, 41 paratypes and 49 non-type specimens collected on seven dates from November 1999 through June 2000. Only specimens above 4 mm carapace length were used for the description. Characters were drawn with a camera lucida and measured to 0.01 mm; proportional summaries report medians, ranges and varying sample sizes from 73 to 83. The treatment compared the new species with published N. anhuiensis and topotypic N. ishigakiensis morphology.
Experimental unit: Individual field specimen for morphological ratios and qualitative seasonal comparison; the paper does not report the female or egg denominator underlying its egg-size and 21-to-82 clutch ranges
Environment: Field-collected from the lower part of a headwater reach in the upper Nakama River, described as about 5 to 10 m wide, approximately 1 m deep and slow-flowing, where shrimp occurred on aquatic vegetation and tree roots with Macrobrachium shokitai; no water chemistry or temperature was reported
Endpoints: deposited type and non-type material, rostrum armature and length, pterygostomian spine, pereiopod proportions, season-associated third-pereiopod form, male first and second pleopod morphology, egg dimensions and reported clutch range, habitat and distribution description.
What it can support: The 2006 morphological treatment supports recognizing N. iriomotensis within its stated species concept and distinguishes its sampled material from N. anhuiensis and N. ishigakiensis using combinations of rostrum, pterygostomian-spine, pereiopod and male pleopod characters. It also documents that the third pereiopod showed sex-associated form in summer specimens but no sexual difference in winter specimens, demonstrating that season can affect the availability of an identification character.
What it cannot support: All listed material came from one named upper-reach locality in the Nakama River, and qualitative wording that the shrimp was common lacks sampling effort and a population denominator. No molecular analysis was included; proposed headwater ecomorph populations had intermediate rostrum lengths and were retained only tentatively pending molecular and ecological study. Published comparisons relied partly on earlier descriptions rather than a balanced multi-population validation, character sample sizes varied because not every specimen contributed every ratio, and no blind key-performance test was conducted. Egg and clutch ranges lack female, clutch and egg denominators. The paper reports no water temperature, pH, hardness, conductivity, dissolved oxygen, nitrogen measurements, diet, culture comparison or aquarium outcome. It cannot identify an aquarium animal from colour or one photograph, authenticate a seller line, prove genetic separation or reproductive isolation, map the complete species range, establish population abundance, or supply a care target, breeding forecast or seasonal aquarium rule.
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