What should a Neocaridina tank contain?

Evidence review: August 12, 2026

A shrimp tank needs functions, not a shopping list. It needs measured water, nitrogen processing, conditioned grazing surface, refuge, guarded equipment and a maintenance path. No controlled Neocaridina davidi study found in this review establishes one required substrate, plant species, leaf product, depth or aquascape style.

Separate the six jobs

Inert, active and bare-bottom tanks can answer different goals

Inert sand or gravel is our house default because it is not meant to control carbonate chemistry. That makes source and replacement water easier to reproduce. It is a process choice, not evidence that inert substrate is healthier.

Active aquasoil can exchange ions and alter alkalinity and pH. The direction and size of that effect depend on the exact product, source water, age and maintenance. Measure source, replacement and tank water instead of banning or recommending every active soil as a category.

Bare bottom can make quarantine, waste removal and animal counts easier. It still needs conditioned filter or habitat surfaces, refuge and verified nitrogen processing. The absence of bottom substrate is not the absence of habitat.

What dark backgrounds actually changed

In short laboratory choice trials, adult females from brown, red and white morphs selected black over white background. They did not significantly distinguish the darker grey levels in the next trial, and the animals appeared darker on darker backgrounds.¹ This was a one-hour choice design after one hour of acclimation, not a chronic health, reproduction or stress experiment.

A separate 90-day study assigned juveniles to white, red or black backgrounds. Females on black had more astaxanthin and a larger relative coloured carapace area than females on white or red. In its second experiment, shelters did not alter the colour measurements, while black background still did.² That supports background standardization for photography and grading. It does not show that black substrate changes genotype, prevents illness or reduces stress.

Offer structure, but keep the result bounded

One direct study placed groups of ten males, non-ovigerous females or ovigerous females in 23-litre tanks with Java moss, wood, Egeria and rock shelters of about 250 cm² each. Five groups of each reproductive class were observed every three hours for 72 hours. Across observations, 82.1% of shrimp were sheltered; use was higher by day than night. Java moss was used most, followed by wood, while rock was used least.³

This supports offering accessible, branching or creviced structure. It does not establish an ideal moss quantity, prove that one plant species is necessary, show survival improvement, or guarantee protection from a fish. A shrimp being hidden is also not proof of stress, and a visible shrimp is not proof of comfort.

Java moss, wood, Egeria and rock differed in material, shape and structural complexity, so the experiment did not isolate which feature drove the choices. The same aquarium groups were counted repeatedly, but the analysis does not state a repeated-measures or aquarium-level model. Shrimp were not fed during the 72 hours, and nighttime observations used a red lamp. There was no empty-tank shelter control and no stress, survival, growth, reproduction or predator endpoint.

Light colour changed location counts, not proven welfare

An open 2018 dissertation tested adult red N. davidi with white, blue, red and green LEDs. Each 15 litre aquarium had two dishes of black stones. One coloured lamp illuminated the left dish, and the observer repeatedly counted shrimp in the lit dish, the unlit dish and elsewhere.⁶ The reported mean count in the lit dish was highest under red and almost zero under blue in both trials. That is a colour associated location count in this apparatus. It is not evidence that red is the healthiest aquarium light or blue is harmful.

The first trial kept one colour on each aquarium, so colour and tank could not be separated. The second trial rotated lamps every five days across four fixed groups, which is a stronger design, but the lamp order, carryover handling and full repeated count model were not reported. Lamp output was not measured or equalized, the lit area always stayed on the left, observer blinding was not reported, and coloured light can change how easily red shrimp are seen. The stated 8 pm to 8 am light period also does not overlap the stated 9 am to 7 pm observation schedule. No stress marker, growth comparison, survival comparison or reproductive rate was measured.

For an ordinary tank, choose a stable day and night schedule that serves the planted system and still provides shade and shelter. Record the timer, lamp, intensity setting and major changes. This review does not identify a required colour, intensity or photoperiod for Neocaridina.

Conditioned surface is valuable, but not self-explanatory

In a purpose-built zero-water-exchange system, researchers evaluated biofilm on plastic net, plastic sheet and agrovelo, then reproduced adults and reared juveniles. The film, composed mainly of microalgae, diatoms, cyanobacteria and ciliates, was the sole diet. Juvenile survival, biomass and biochemical reserves were higher with plastic net and agrovelo than with the other tested treatment, and the life cycle was completed.⁴

That is strong evidence for deliberately conditioned surface in the tested culture system. It is not evidence that every film on every moss, leaf or tank wall has the same community, quantity or nutritional value. It also does not certify a tank as cycled or make measured prepared food unnecessary in a different system.

Leaves, cones and wood are inputs, not medicine

Leaf claims need separate endpoints. Choosing a leaf does not prove that it is a complete food. Faster litter breakdown does not reveal how much leaf tissue was eaten, whether water quality improved, or whether shrimp survived, grew and reproduced better. One leaf-choice study remains in the full-text screening queue. A separate 140-day microcosm study has now cleared method review. It compared litter alone, direct shrimp contact with feces separated, feces contact without direct shrimp contact, and shrimp, litter and feces together.⁵

The direct-contact buckets lost more cattail litter mass by day 140. That result supports faster breakdown under the tested conditions, not a measured amount eaten. Contact also allowed microbial grazing, fragmentation and physical disturbance. Eight river-collected shrimp occupied four litres, filtered river water was replaced weekly, and the study measured decomposition, enzymes and water chemistry rather than growth, condition, molting or reproduction. It does not turn cattail, catappa or alder into a complete food or a universal leaf schedule.

• They can add surface, decomposing organic matter and visible water colour. Each also changes the tank over time and may carry a source or treatment history.
• This review found no controlled N. davidi trial showing that catappa leaves or alder cones prevent disease, cure infection, provide a complete diet or require a fixed replacement schedule.
• Tannin-stained water is an observation, not a medication dose. Remove or replace a botanical for a recorded goal such as inspection, decomposition, water trend or habitat renewal, not because a universal calendar says to.

Choose a layout you can operate

Injected CO2 is a plant system, not a shrimp requirement or automatic prohibition. It changes carbonate chemistry, so record dose method, light period, actual pH and gas-exchange conditions. This review found no controlled N. davidi study establishing a required photoperiod, required plant species or universal safe CO2 recipe. A direct thesis found a short colour associated location signal in intact shrimp but did not establish welfare or a home lighting regime. Two recent direct molecular papers also report short light response changes after eyestalk gene knockdown, and one reports a longer molt cycle. Their complete methods were not publicly accessible in this review. Together these sources justify more research, not a spectrum, intensity, photoperiod or molt timing instruction.

Before anything wet enters the tank

1. Record seller, date, species or product, source system and known treatments.
2. Keep an unknown wet source out of production and quarantine. Use a separate, commissioned plant or observation system and dedicated tools.
3. Rinse loose material away, but do not treat rinsing as proof that pesticide, medication, fertilizer, epibionts or eggs are absent.
4. Change one habitat input at a time when possible. Record water and animal baselines before and after the addition.
5. During maintenance, inspect siphoned water for juveniles and avoid cleaning all conditioned surfaces at once.

Use the chemical-safety guide for wet-transfer and suspected-exposure decisions, the cycling guide for nitrogen-processing evidence, the feeding guide for biofilm and diet, the grazing and cleanup guide for surface claims, the organism-identification guide for unexpected worms or polyps, and the maintenance guide before disturbing substrate or filter media.

Claims this evidence does not support

• Shrimp require a planted tank, active soil or dark substrate.
• Black substrate reduces stress or improves genetic grade.
• Java moss guarantees shrimplet survival or protection from fish.
• A visible biofilm proves a tank is cycled or provides a complete diet.
• Catappa leaves cure disease or must be replaced on a fixed schedule.
• A bare-bottom tank cannot provide appropriate habitat.
• A rinse or tissue-culture label certifies a plant free of every hazard.
• Red light is healthiest, blue light is harmful or one colour attracts every shrimp.

Sources

1. Maciaszek et al., 2021. All Shades of Shrimp: Preferences of Colour Morphs of a Freshwater Shrimp Neocaridina davidi for Substrata of Different Colouration. Animals 11(4): 1071.
2. Tomas, Sganga and López Greco, 2020. Effect of background color and shelters on female pigmentation in the ornamental red cherry shrimp Neocaridina davidi. Journal of the World Aquaculture Society 51: 775-787.
3. Carvalho-Batista et al., 2023. Shelter preference and variation in the daily activity pattern of the ornamental shrimp Neocaridina davidi. Nauplius 31: e2023018.
4. Viau et al., 2020. Breeding and life cycle of the ornamental freshwater shrimp Neocaridina davidi in a biofilm-based culture system. Aquaculture Research 51: 3847-3864.
5. Kong et al., 2019. Promotive performance of shrimp Neocaridina denticulata on Typha angustifolia leaf litter decomposition. Hydrobiologia 827: 75-87.
6. Marques, 2018. Estudos do comportamento do camarão Neocaridina davidi var red quando exposto a diferentes espetros de luz. University of Lisbon integrated MSc dissertation in Veterinary Medicine.