Controlled experiment
Direct Neocaridina evidence
Carvalho-Batista et al., 2023. Nauplius 31: e2023018.
Source taxon as published: Neocaridina davidi
Study shape: Ten shrimp from one sex or reproductive class shared an aquarium offering Java moss, wood, Egeria and rock shelters of about 250 square centimetres each. Shelter positions were varied, and the same group was counted repeatedly during eight 20-minute periods per day for three days.
Experimental unit: Ten-shrimp aquarium group, with five consecutive groups per sex or reproductive class and repeated observations of the same animals across 72 hours
Environment: Fifteen 23-litre laboratory aquarium groups at 23 C under a 12-hour light and 12-hour dark cycle, with red incandescent light used for night observations and no feeding during the 72-hour experiment
Endpoints: overall shelter occupancy, occupancy by shelter type, day and night shelter use, walking and swimming frequency.
What it can support: Across the tested groups, mean shelter use was 82.1 percent per observation, shelter use was higher by day than night, and Java moss was used most overall, followed by wood, while rock was used least.
What it cannot support: Shelter material, shape and structural complexity changed together, so the comparison does not isolate a live-plant, moss-species or complexity effect. The paper does not state a repeated-measures or aquarium-level model for the many observations of the same groups. Animals were not fed during the 72 hours, night observations used a red lamp, and no no-shelter, predator, stress, survival, growth or reproduction outcome was tested. The result does not make one plant required, define an ideal hidden percentage, diagnose stress or prove protection from fish.
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Controlled experiment
Direct Neocaridina evidence
Maciaszek et al., 2021. Animals 11(4): 1071.
Source taxon as published: Neocaridina davidi
Study shape: Groups of three same-morph shrimp were acclimated for one hour and filmed for one hour across shade, colour and pattern choices, usually with eight dish replicates.
Experimental unit: Dish containing three shrimp, not each occupancy observation
Environment: Short laboratory choice trials in circular dishes at 20 to 21 C with printed shade and pattern backgrounds
Endpoints: time in background zones, shade choice, pattern choice, photographic body shade.
What it can support: The tested morph groups preferred darker over lighter backgrounds during the short choice trials, with some morph-specific pattern results.
What it cannot support: The trials did not measure long-term welfare, stress, growth, survival, reproduction or a required aquarium substrate.
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Controlled experiment
Direct Neocaridina evidence
Tomas, Sganga and López Greco, 2020. Journal of the World Aquaculture Society 51(3): 775-787.
Source taxon as published: Neocaridina davidi
Study shape: Background and shelter conditions were assigned and female pigmentation was followed for 90 days.
Experimental unit: Treatment aquarium
Environment: Laboratory background and shelter treatment
Endpoints: visible pigmentation, astaxanthin.
What it can support: Background can change measured visible pigmentation under a defined protocol.
What it cannot support: It does not establish that dark substrate changes genotype, prevents stress or improves inherited grade.
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Controlled experiment
Direct Neocaridina evidence
Viau et al., 2020. Aquaculture Research 51: 3847-3864.
Source taxon as published: Neocaridina davidi
Study shape: The full life cycle and juvenile outcomes were followed while comparing conditioned artificial substrates.
Experimental unit: Substrate treatment culture unit
Environment: Designed laboratory biofilm culture across substrate treatments
Endpoints: juvenile survival, growth, biomass, biochemical reserves, reproduction.
What it can support: The tested biofilm community supported the life cycle and substrate treatment changed juvenile outcomes.
What it cannot support: It does not establish that any home-aquarium film is complete food or that tank age measures grazing value.
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Controlled experiment
Direct Neocaridina evidence
Kong et al., 2019. Hydrobiologia 827: 75-87.
Source taxon as published: River-collected Neocaridina denticulata, retained as published
Study shape: Four treatments separated litter alone, direct shrimp contact with feces falling away, feces contact without direct shrimp contact, and shrimp plus litter plus feces together. Each shrimp unit held eight animals and 3 g of air-dried cattail litter. Four independently prepared buckets represented each treatment at each 35-day destructive harvest, for 64 buckets total. Filtered river water was replaced weekly.
Experimental unit: Four-litre bucket, with four independent buckets per treatment and harvest time; the paper describes destructive treatment-by-time units but reports date as a repeated factor without explaining how repeated units were linked
Environment: Sixty-four aerated four-litre river-water microcosms in an environmental chamber set to 20 C, with measured water varying from 20 to 25 C during 140 days
Endpoints: cumulative litter dry-mass loss, decomposition coefficient, interval mass loss, leaf-associated extracellular enzyme activities, pH, chemical oxygen demand, ammonium nitrogen, nitrate nitrogen, total nitrogen, total phosphorus.
What it can support: After 140 days, cumulative litter mass loss was 51.7 percent in litter-only controls, 83.4 percent where shrimp contacted litter but feces fell away, 57.8 percent where feces contacted litter without shrimp contact, and 84.5 percent where shrimp, litter and feces remained together. The treatment contrasts support faster breakdown when shrimp had direct access under this microcosm protocol; water chemistry and enzyme responses also differed among treatments.
What it cannot support: Litter mass loss is not measured ingestion. Direct shrimp access combines grazing on leaf tissue or associated microbes, fragmentation and physical disturbance, while the reported grazing and feces shares were derived from treatment contrasts rather than measured intake. The experiment used one river population, one cattail preparation, eight shrimp in four litres and filtered river water replaced weekly, which the discussion says helped provide food; no formulated-food baseline was described. Reported zero mortality does not establish dietary adequacy because growth, condition, molting, reproduction and health were not measured. The paper switches between Typha angustifolia and Typha orientalis in treatment text and figure material, gives conflicting one-week versus one-to-two-day animal holding descriptions, does not report random allocation, lacks an obvious sham-mesh control, and does not reconcile destructive harvest with repeated-measures analysis. It also labels P values above 0.05 through 0.10 as biologically significant but noisy. The result does not recommend cattail, catappa or alder, establish a ration or replacement interval, prove a complete diet, or promise home-aquarium water safety.
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Controlled experiment
Direct Neocaridina evidence
Marques, 2018. Integrated MSc dissertation in Veterinary Medicine, University of Lisbon.
Source taxon as published: Commercial adult shrimp labelled Neocaridina davidi var red; no morphological or molecular identification method was reported
Study shape: The first four-week trial placed a new 15-shrimp group in each of four aquaria each week while one lamp colour remained assigned to each aquarium. The second 20-day trial kept four 15-shrimp groups in their aquaria while rotating the four lamps every five days. An observer counted shrimp inside the lit Petri dish, inside the unlit Petri dish and elsewhere every five minutes during five one-hour periods per day. Lamp spectra were reported as relative spectral distributions, and the lit-dish count was analysed with a generalized linear mixed model followed by Tukey comparisons.
Experimental unit: In the first trial, aquarium and light colour were completely confounded even though four successive shrimp groups entered each tank. In the second, aquarium-period was the assigned unit, giving four five-day tank-periods per colour while the same four groups were counted repeatedly. The thesis reports 5,200 count occasions per trial but does not state the model formula, response family, random effects, repeated-measures correlation, lamp order or carryover treatment.
Environment: Four 15-litre aquaria at a reported 23 C, pH 7 and 60 mg/L GH, each holding 15 adults and two Petri dishes of black stones, with only the left dish illuminated by a white, blue, red or green Marina LED
Endpoints: number inside the lit Petri dish, number inside the unlit Petri dish, number elsewhere in the aquarium, qualitative movement, observed mortality, births and molts.
What it can support: Under this two-dish apparatus, the mean number counted inside the lit dish differed by lamp colour in both trials. Reported lit-dish means were 3.70 red, 1.76 green, 0.93 white and 0.03 blue in the first trial, and 4.03 red, 1.74 green, 1.32 white and 0.01 blue in the rotating-lamp trial. The result supports a short-term colour-associated location-count signal that merits a better controlled replication.
What it cannot support: The thesis does not establish a preferred aquarium spectrum or a welfare ranking. It compared one coloured lit area with one dark area rather than offering simultaneous colour choices, kept the lit area on the left, did not measure or equalize irradiance or illuminance, reported only normalized spectral shapes and did not report observer blinding. Red shrimp can also differ in detectability under different coloured lamps. The stated 20:00 to 08:00 light period does not overlap the stated 09:00 to 19:00 observations, leaving the exposure timing internally unresolved. The first-trial methods state 240 adults while the abstract states n = 120. Phase one cannot separate lamp colour from aquarium; phase two does not report lamp sequence, washout or carryover control; and the statistical formula and random effects are absent despite thousands of correlated repeat counts. Sex, individual identity, lamp output drift and births entering counts were not resolved. No stress biomarker, growth, survival comparison, reproductive rate or chronic colony outcome was measured. Absence of observed deaths and incidental births or molts cannot show comfort, health benefit or reproductive superiority. Do not recommend red light, warn against blue light, specify a spectrum or photoperiod, infer colour vision, or use lamp attraction as a capture method from this study.
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Controlled experiment
Direct Neocaridina evidence
Groendahl and Fink, 2017. Scientific Reports 7: 44869.
Source taxon as published: Neocaridina davidi within a three-grazer freshwater model
Study shape: One to three grazer species were assigned to defined algal communities for three days, then grazer richness and phosphorus were combined in a one-week factorial experiment.
Experimental unit: Three-hundred-millilitre flask, with six to eight usable replicates depending on comparison
Environment: Laboratory flasks containing defined green-algal communities at 20 C
Endpoints: algal cell count, algal biovolume, algal species richness, algal diversity and evenness.
What it can support: Neocaridina davidi reduced several tested algae and showed a relative preference for Closterium moniliferum in the three-day model.
What it cannot support: The defined short flask experiment does not establish hair-algae control, a cleaning rate, a complete diet or whole-aquarium nutrient export.
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Controlled experiment
Direct Neocaridina evidence
Viau et al., 2016. Aquaculture Research 47(8): 2528-2542.
Source taxon as published: Neocaridina heteropoda heteropoda
Study shape: Water quality, biofilm processes, survival and growth were measured in a designed culture system.
Experimental unit: Culture vessel or substrate treatment unit
Environment: Aerated laboratory biofilm culture with zero routine water exchange
Endpoints: nitrogen compounds, dissolved oxygen, survival, growth.
What it can support: A deliberately designed and aerated biofilm system can contribute to water processing and juvenile culture.
What it cannot support: It does not validate an unaerated jar, every visible home biofilm, a no-water-change rule or a filterless aquarium.
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