Controlled experiment
Direct Neocaridina evidence
Guz et al., 2026. Journal of Fish Diseases 49(7): e70127.
Source taxon as published: Ornamental Neocaridina spp.
Study shape: Five isolates were identified biochemically and by mass spectrometry, screened for virulence genes, challenged back into shrimp and tested for drug susceptibility.
Experimental unit: Infection challenge group or bacterial isolate, depending on endpoint
Environment: Diagnostic isolation followed by laboratory pathogenicity challenges and antimicrobial susceptibility testing
Endpoints: isolate identity, virulence genes, challenge mortality, lesion reproduction, antimicrobial susceptibility.
What it can support: The tested isolates reproduced disease in challenge animals with isolate-specific mortality and multidrug-resistance patterns.
What it cannot support: A dark lesion or lethargy cannot identify Aeromonas, and isolate resistance results do not authorize an aquarium antibiotic or dose.
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Review or synthesis
Broader ornamental-shrimp review
Holroyd et al., 2026. Conservation Physiology 14(1): coag046.
Source taxon as published: Tropical ornamental shrimp, including Neocaridina literature
Study shape: Published physiology, trade and transport evidence was synthesized and major gaps were identified.
Experimental unit: Published source, not a new animal experiment
Environment: Review of aquarium trade and transport evidence
Endpoints: temperature evidence, oxygen evidence, carbonate chemistry, nitrogen waste, health assessment.
What it can support: The review maps major species-specific evidence gaps and relevant transport stressors.
What it cannot support: It does not validate a drip rate, package, forecast gate, water target or treatment for Neocaridina.
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Morphology or taxonomy
Direct Neocaridina evidence
Kusmintarsih et al., 2025. E3S Web of Conferences 609: 02003.
Source taxon as published: Market-labeled Neocaridina denticulata and Neocaridina palmata; no host-identification method reported
Study shape: One hundred market-labeled N. denticulata and 100 market-labeled N. palmata were transported in market aquarium water. Gill and cephalothorax material was scraped onto slides and examined by microscopy for organisms reported as sessile bdelloid rotifers, Vorticella sp. and Zoothamnium sp.
Experimental unit: Individual examined shrimp, clustered within an unreported number of sampled aquariums from one seller and one claimed river source
Environment: Two hundred shrimp sampled across more than eight aquariums operated by the only ornamental-shrimp seller at one fish market in Purbalingga, Central Java, Indonesia
Endpoints: presence of reported organism group, host label, reported sex, gill or cephalothorax location.
What it can support: In this one-seller sample, the authors reported at least one of the three organism groups on 156 of 200 examined shrimp, including 78 of 100 under each market species label.
What it cannot support: Aquarium identities and sample counts, collection dates, host-species identification, sexing method, microscope magnification, diagnostic key, stain, image vouchers, molecular confirmation, examiner blinding, confidence intervals and the named statistical test were not reported. The two market labels were reportedly kept together, and the analysis did not account for aquarium clustering. No tissue damage, respiration, behaviour, growth, reproduction, mortality, transmission, treatment or causal disease endpoint was measured. The 78 percent result is not a trade-wide prevalence estimate, does not validate a home diagnosis, does not prove every detected organism was parasitic or harmful and does not establish a treatment indication.
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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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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
Direct Neocaridina evidence
Hoitsy et al., 2023. Magyar Allatorvosok Lapja 145(6): 351-358.
Source taxon as published: Owner-submitted captive Neocaridina davidi from multiple breeders; host-identification method not reported
Study shape: Owners submitted 15 shrimp from different breeders after seeing moving white organisms on the day of introduction or within the following days. The shrimp were photographed, and associated live worms were collected into water drops, examined by stereomicroscopy and light microscopy, and identified from stated morphological references.
Experimental unit: Selected submitted shrimp for carrier observations and an unreported number of removed worms for morphological identification; five shrimp shared each of three holding aquaria, but no treatment or outcome comparison was assigned
Environment: Fifteen selected diagnostic submissions held five per approximately 18-litre aquarium at reported pH 6.8, conductivity 300 microsiemens and 25 C during examination
Endpoints: visible worm count and body region, worm length, live worm morphology, species identification, presence of worm eggs in the branchial chamber.
What it can support: All 15 selected shrimp carried visible opalescent-white moving worms, with 2 to 8 observed on the head, antennae or rostral region. Examined worms were reported as 0.8 to 2.0 mm long and identified as Scutariella japonica using paired anterior projections, two eyespots, internal reproductive anatomy and a posterior horseshoe- or heart-shaped sucker. Some worms contained eggs, and eggs were visible through the lateral carapace in the branchial chamber.
What it cannot support: This was a selected diagnostic case series, not a prevalence, transmission, quarantine-duration, water-quality or source-risk study. Host identity was not independently verified, source counts and clustering were not reported, the number of worms examined was omitted, and no molecular confirmation, voucher or image-accession record was stated. The study measured no respiration, gill lesion, molting failure, growth, reproduction, mortality, spontaneous clearance or treatment outcome. Harm statements were literature synthesis, not observations in these 15 shrimp. Fenbendazole was mentioned in one discussion sentence without product, dose, exposure, allocation, control, efficacy, recurrence or host-safety data. It cannot support a treatment recipe, a claim that every white worm is S. japonica or use of treatment response as diagnosis.
Related source material: University of Veterinary Medicine Budapest repository record and open PDF
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Morphology or taxonomy
Direct Neocaridina evidence
Maciaszek et al., 2023. Animals 13(10): 1616.
Source taxon as published: Neocaridina davidi
Study shape: One hundred shrimp from each of three locations within each source category were inspected individually in rostral, branchial, pereiopodal and pleopodal regions. Epibionts were isolated under clove-oil and ethanol sedation, identified morphologically at 500 to 1500x, and followed by an incompletely reported two-week quarantine observation. Prevalence models used source category and sex, microhabitat models used body region, and Spearman correlations assessed co-occurrence, egg production and molting.
Experimental unit: Individual examined shrimp nested within nine source locations and their transport bags; the reported individual-level GLMs do not describe source location or bag as a cluster or random effect
Environment: Nine hundred approximately 2.0 cm shrimp collected in November 2018 from three wild sites, three aquaculture-pond sources and three aquarium sources in Taiwan, then air-freighted in habitat water to Poland and inspected after a 10-hour acclimation in the transport-bag water
Endpoints: morphological identity and measurements, prevalence and mean intensity, co-occurrence, body-region distribution, egg-production association, molting association, observed cuticle traces and recolonization after molt.
What it can support: The authors distinguished Cladogonium kumaki, Monodiscus kumaki, Scutariella japonica and Holtodrilus truncatus, plus ciliates and rotifers. At least one recorded epibiont occurred on 688 of 900 shrimp and H. truncatus on 390 of 900. All four named taxa occurred in all four body regions with different distributions; H. truncatus was relatively associated with rostral and pereiopodal regions. Live H. truncatus and temnocephalids were observed leaving shed exuviae and seeking a host, sometimes recolonizing the nearby original shrimp.
What it cannot support: The source categories were observed, not assigned treatments, and are represented by only three locations each. Transport, ten-hour acclimation and microscopy handling may have changed organism abundance or location. Source-level clustering was not included in the reported GLMs, the sample was strongly female-skewed, and the sexing method was not stated. Morphological identification required microscopy and does not validate a phone-image diagnosis. Egg and molt analyses were correlational; the H. truncatus molt row reports rho -0.26 with p 0.847, an internally inconsistent combination for the surrounding interpretation. The quarantine allocation, denominator, water conditions, removal exposure and outcome measurements were not fully reported. Molting did not clear live worms, and the paper did not assign or compare a salt, medication or home-removal treatment. The sample is not prevalence for every seller, home colony or geographic trade route.
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Morphology or taxonomy
Neocaridina identity evidence
Kakui and Komai, 2022. Aquatic Animals 2022: AA2022-1.
Source taxon as published: Neocaridina sp. aff. davidi
Study shape: Associated worms and host shrimp were examined for a regional record and taxonomic identification.
Experimental unit: Collected host or associated worm specimen
Environment: Field-collected host and associated worm specimens from Hokkaido, Japan
Endpoints: worm identification, host association, regional occurrence.
What it can support: A method-based record of Scutariella japonica associated with the source host identification.
What it cannot support: Occurrence does not establish aquarium prevalence, severity, treatment efficacy or identification from a distant white shape.
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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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Field observation
Direct Neocaridina evidence
Bauer et al., 2021. Diseases of Aquatic Organisms 146: 107-115.
Source taxon as published: Neocaridina davidi
Study shape: Twenty submitted shrimp were assessed with clinical examination, wet mounts, microbiology, histology and sequencing of green pleopodal structures.
Experimental unit: Submitted shrimp, tissue section or algal sample, depending on method
Environment: Diagnostic examination of an imported commercial group during a multifactorial outbreak
Endpoints: organism morphology, sequence placement, cuticle penetration, co-occurring microbes, outbreak mortality history.
What it can support: The green organism was placed near Trentepohliales and rhizoids were observed penetrating cuticle into subcutaneous tissue.
What it cannot support: The multifactorial case does not assign every death to the alga, establish prevalence or let a green phone image confirm the organism.
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Morphology or taxonomy
Direct Neocaridina evidence
Ahn and Min, 2016. Journal of Species Research 5(3): 459-462.
Source taxon as published: Wild stream shrimp identified only as Neocaridina sp.; no host voucher, diagnostic method or molecular host identification reported
Study shape: The authors removed worms from preserved host exoskeletons under a stereomicroscope, described external and internal morphology, deposited examined material at Inha University and the National Institute of Biological Resources, and extracted whole-body DNA from one worm for partial mitochondrial COI amplification and sequencing.
Experimental unit: An unreported number of Neocaridina hosts and removed worms across three collection dates; one whole worm for the 674-base-pair COI sequence; three National Institute of Biological Resources voucher identifiers were listed
Environment: Hand-net collections from Andeok Valley, Jeju-do Province, South Korea on 23 June 2010, 23 August 2015 and 18 May 2016; hosts were preserved directly in 95 percent ethanol at the collection site
Endpoints: geographic and host occurrence, whole-body and jaw morphology, body length, voucher deposition, partial mitochondrial COI sequence.
What it can support: The record establishes morphologically identified H. truncatus on wild Neocaridina sp. at one South Korean stream across material dated in 2010, 2015 and 2016. Described characters included a transparent terete body under 2 mm, no trunk appendages, a posterior sucker about the diameter of the head region and paired jaws with a 7/7 dental formula. Three NIBR voucher identifiers and the first reported 674-base-pair COI sequence for the genus, GenBank KX683299, provide checkable taxonomic anchors.
What it cannot support: The paper does not state the number of hosts collected, hosts carrying worms, worms examined per date, worms per host, sampling effort or whether absence was assessed, so three dated collections do not estimate prevalence, persistence between dates or geographic range. The host remained Neocaridina sp. without a reported voucher or molecular identification. Although examined material was deposited at two institutions, only three NIBR identifiers were listed and the paper does not map individual morphology, image, sequence and voucher records. The single COI sequence created a barcode reference but was not compared with an existing conspecific sequence or used in a phylogenetic or species-delimitation analysis. Immediate ethanol preservation precluded live attachment, movement and host-response observations. The study measured no lesion, respiration, molting, growth, reproduction, mortality, transmission, origin, treatment, recurrence or host safety. It cannot establish N. davidi prevalence, aquarium-trade origin, harmlessness, a phone-image diagnosis, a quarantine duration or a treatment protocol.
Related source material: Korea Citation Index open article record and licensed PDF
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System observation or method study
Direct Neocaridina evidence
Tanaka, Wada and Hamasaki, 2016. Zoological Science 33(2): 154-161.
Source taxon as published: Holtodrilus truncatus; field hosts included Paratya compressa, Caridina leucosticta, Caridina multidentata, Caridina typus and Neocaridina denticulata
Study shape: The field survey standardized dip-net sampling at ten waterside areas per site and repeated one river seasonally. The salinity study exposed 24, 20, 30, 25 and 12 host-removed worms to nominal 0, 0.5, 1, 1.5 and 3 percent salinity without food, with observation intervals that shortened as salinity rose. Host-choice tests placed one worm with a size-matched pair of Paratya compressa, Caridina leucosticta or Caridina multidentata for 40, 36 and 39 pairwise replicates.
Experimental unit: Field host shrimp for occurrence endpoints; an incompletely reported small plastic tank holding two or five isolated worms for salinity exposure; and one worm with one two-shrimp species pair for each host-choice replicate
Environment: Field collections at one to eight sites in each of 26 rivers on the Kii Peninsula, Japan, plus 22 to 27 C freshwater laboratory salinity and two-host choice tests
Endpoints: river and host occurrence, prevalence and intensity on Paratya compressa, host body location, Paratya compressa egg number association, isolated-worm attachment-defined survival, selected host in pairwise choice.
What it can support: Holtodrilus truncatus occurred in 10 of 26 surveyed rivers and on five atyid host species. The only two examined N. denticulata were both recorded with the worm, which establishes occurrence but not prevalence. Isolated-worm survival declined with increasing nominal salinity, including significantly lower survival at 0.5 than 0 percent. In pairwise tests that excluded Neocaridina, worms selected P. compressa over both Caridina species and C. leucosticta over C. multidentata. Cohabitation was not associated with egg number in the measured P. compressa model.
What it cannot support: The direct Neocaridina result is two field animals, not a representative sample. No Neocaridina entered the salinity, host-choice or egg-number analyses. Worms were removed after the host carapace was detached, so salinity was tested on isolated organisms rather than attached worms or living host shrimp. The work measured no treatment efficacy on a host, shrimp survival, sublethal host effect, recurrence or safety margin. Worms shared exposure containers in groups of two or five, the number of independent tanks was not reported, checking frequency differed by concentration, no food was provided, and floating or failure to attach was classified as death. Nominal salinity tolerance cannot validate a salt dip, 30-second exposure, host-safe dose or Neocaridina host preference.
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System observation or method study
Direct Neocaridina evidence
Niwa et al., 2014. Central European Journal of Biology 9(1): 80-85.
Source taxon as published: Wild Sugo River shrimp identified only as Neocaridina spp.; the catch could include native N. denticulata denticulata and imported Neocaridina lineages
Study shape: The authors collected 271 host shrimp across nine years, mapped H. truncatus body locations on 141 hosts in 2011, measured 23 cocoons, observed 15 host-removed worms from 14 shrimp in no-added-food survival containers, and placed five removed worms sequentially with a reported pool of 28 potential host shrimp across several taxa.
Experimental unit: Individual host for mapped attachment location; individual cocoon for diameter; nominally individual host-removed worm, although only 13 of 15 worms receive a reported container and survival range; and an unresolved sequence of five worms exposed one host at a time in the host-exchange demonstration
Environment: Field collections at three Sugo River stations from 2003 to 2011 plus laboratory observations in source river water, aerated aquaria, individual bottles, dishes and 100 mL vials
Endpoints: host body location, cocoon diameter and embryo count, observed hatching and gill-chamber entry, days survived after host removal, attachment or predation during host exchange, movement from deteriorating to surviving captive hosts.
What it can support: Among 141 mapped wild hosts, reported H. truncatus locations were 55.3 percent between the first pleopod and fifth pereiopod, 17.0 percent on the carapace, 15.6 percent at the eye base, 8.5 percent on the antennule and 3.6 percent around the egg mass. Twenty-three cocoons measured 0.58 to 0.76 mm, and the largest observed cocoon contained 14 developing worms. Ten worms in 100 mL vials survived 7 to 46 days and three in dishes survived 12 to 21 days after host removal without added food. In the host-exchange observation, all five supplied worms attached to Neocaridina hosts within three hours.
What it cannot support: Host shrimp were resolved only to Neocaridina spp. in a river where native and introduced lineages were discussed, so the findings are not species-specific N. davidi evidence. The 271 total catch, 152 animals mentioned in the attachment procedure and 141 mapped hosts are not fully reconciled, station and date denominators are missing and the location percentages do not state whether each host contributed one location or all worms were counted. No molecular confirmation of host or worm identity was reported in this article. The survival containers differed in volume, light and temperature, two of 15 worms are absent from the reported ranges, ages were unknown, water was not renewed or analytically described, death criteria were not stated and there was no fed or host-present control. The five-worm host exchange omitted exposure order, reuse mapping, independent replication, container details and complete outcomes for 28 potential hosts. Disappearance under an opaque crayfish carapace was interpreted as migration rather than directly confirmed. Claims that egg-bearing hosts hatched healthy young had no defined denominator, comparison or follow-up. Observed migration from deteriorating hosts does not establish transmission probability or a quarantine duration. The study measured no controlled shrimp lesion, respiration, growth, reproduction, mortality causation, treatment efficacy, recurrence or host safety and cannot validate predatory tankmates, forced host deterioration, worm collection, medication or a fixed isolation period.
Related source material: German National Library open full-text copy
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