Amano Shrimp Care Guide

Start with a mature, filtered aquarium and a planned group, not a shrimp-per-litre calculator. OATA's broad UK guide suggests an aquarium of approximately 20 litres for Amano Shrimp, says social shrimp should usually be kept in groups of at least five, and advises a larger aquarium when fish are included^[7]. Those are cautious planning screens, not controlled Caridina multidentata minima or proof that five fit every 20-litre setup.

The guide and the shop have different jobs. This page explains long-term care. For current availability and prices, use the separate Amano Shrimp shop page or shrimp and crustacean shop hub. A care photograph does not prove that the pictured animal, size or pack is in stock.

Identity: Amano Shrimp and Caridina japonica

The accepted name is Caridina multidentata Stimpson, 1860, in the family Atyidae. Cai and colleagues re-examined the type material and concluded that the familiar older aquarium name Caridina japonica is a junior synonym^[1]. DecaNet and NCBI both use C. multidentata as the current name, with NCBI listing C. japonica as a synonym^[2][3].

The 2006 revision records the main islands of Japan, Ogasawara and Ryukyu Islands, Taiwan, Fiji and Madagascar, and describes the species from large rivers with big rocks on the substrate^[1]. That distribution record does not mean a shop specimen is wild-caught from any named place. Ask the seller what is known about the actual batch.

Source-labelled aquarium photographs can help show the translucent body and lateral dots or dashes, but those marks alone do not authenticate a shipment. Identity should begin with the supplier's scientific name and traceable stock information.

Tank size and group: no per-litre formula

OATA's broad invertebrate guide recommends approximately 20 litres for larger shrimp such as Amanos and at least five for social shrimp^[7]. It also says the tank should be larger with fish. The source combines several shrimp and snail groups, so this page does not promote “one Amano per four litres”, “eight in 40 litres” or any other universal density equation.

Plan in this order:

1. Confirm biological filtration is mature for the intended load.
2. Measure real usable water and footprint after substrate, wood and equipment.
3. Reserve cover and feeding access for a group of at least five under the broad OATA screen.
4. Add every adult fish, snail and other shrimp to the capacity decision.
5. Leave headroom for feeding, maintenance errors and summer temperature.

One surviving shrimp does not create an emergency purchase. Test the system and understand why the group was lost or reduced before adding more animals. Conversely, reaching five does not make an overcrowded aquarium suitable.

Water and temperature in a UK aquarium

OATA's general shrimp-and-snail table gives 17–27°C, pH 6.5–8 and 4–18 dGH, with ammonia and nitrite at zero^[7]. Use those as broad UK trade guidance, not a controlled species-specific tolerance experiment.

In the reproduction study, females laid eggs at all three tested temperatures, but C. multidentata hatching rates were low at 26°C and newly hatched larvae per female declined as temperature increased^[5]. That result is useful evidence that temperature affects biology; it does not prove a single ideal household setting or justify pushing an established aquarium rapidly to 20°C.

UK tap water is not one chemistry. The Drinking Water Inspectorate explains that hardness varies with geology and supply and directs customers to their water company for local information^[9]. Test the aquarium as well: substrate, rocks, top-ups and water treatment can change it. A domestic ion-exchange softener replaces calcium and magnesium with sodium, so “softened” does not automatically mean suitable for shrimp^[10].

Aquarium setup: mature surfaces, cover and safe flow

“Mature” means the biological filter can process the planned waste and testing confirms ammonia and nitrite remain at zero—not that a calendar reached a fixed number of weeks. OATA recommends testing and warns that stocking too quickly can overwhelm the bacterial population^[8].

Provide aquarium-safe wood, rock and planting or other structure that creates grazing surfaces and sheltered areas. Protect filter intakes with an appropriate guard so shrimp cannot enter or become trapped, and keep access for inspection and cleaning. A secure cover also reduces escape risk; seal cable and pipe gaps without blocking required ventilation.

A 2025 laboratory choice study found that C. multidentata preferred a current and avoided light in the tested apparatus^[6]. This supports offering flowing water and shaded options, but it does not prescribe a filter turnover rate or lighting schedule. Maintain gas exchange, avoid blasting the animals around the aquarium, and give them a choice of exposed and sheltered surfaces.

Feeding and honest algae expectations

Amano Shrimp graze surfaces and are used as nuisance-algae helpers, but they are animals, not maintenance equipment. OATA says shrimp can help control nuisance algae and warns that overfeeding leaves waste that degrades water quality^[7]. Neither point establishes that one shrimp will clear hair algae, black beard algae or a whole aquarium on schedule.

Use a suitable complete sinking food as the nutritional base, then provide appropriate variety according to the food maker and the rest of the community. Watch whether every shrimp reaches food. Remove recurring excess and adjust the amount rather than assuming the shrimp will consume all leftovers.

If algae is increasing, investigate the system:

• lighting duration and intensity;
• decaying material and uneaten food;
• plant growth and nutrient balance;
• maintenance and water-test trends;
• whether the “algae” has been identified correctly.

Shrimp may graze some of it while ignoring other growth. Correct the underlying conditions and continue feeding the animals; a spotless-looking aquarium is not evidence that they no longer need nutrition.

Tank mates: risk-screen every adult animal

OATA warns that freshwater shrimp may be eaten by common aquarium fish and advises against fish able to fit them in the mouth or known predators^[7]. Mouth size is only the first screen. A fish can injure, chase or outcompete a shrimp without swallowing an adult, and a newly moulted animal may be more exposed.

Compare:

• adult body and mouth size, not juvenile shop size;
• predatory, territorial and foraging behaviour;
• temperature, pH and hardness overlap;
• feeding speed and whether shrimp can access food;
• hiding choices without trapping the animal;
• group requirements and the actual footprint;
• a workable separation plan if behaviour changes.

Related Neon Tetra, Honey Gourami, Betta and Corydoradinae guides can help compare requirements; none is an endorsement or a promise of shrimp safety. Individual behaviour and aquarium design still matter.

Moulting, hiding and health checks

Shrimp shed an exoskeleton as they grow. OATA notes that an empty moult can resemble a dead shrimp^[7]. Do not diagnose an animal from one shell or from hiding alone. Check whether the shrimp itself is present, observe movement and feeding, and review the entire environment.

When behaviour changes:

1. Measure temperature, ammonia and nitrite immediately, then review nitrate, pH and hardness in context.
2. Check filters, heaters, aeration and recent maintenance.
3. Review new animals, plants, decor, food, sprays and treatments.
4. Compare the affected shrimp with the rest of the group.
5. Record photographs and times; seek specialist aquatic or veterinary help when signs persist or are severe.

OATA provides a UK fish-vet directory^[12]. A page cannot distinguish a normal moult, failed moult, poisoning, predation or disease from “lying on its back”, colour or disappearance alone.

Copper and medicines: read the actual label

Copper toxicity is real, but an absolute internet threshold is not. Ravaux and colleagues measured an acute median lethal concentration of 1.15 mg/L under their particular laboratory conditions and found that sublethal pre-exposure impaired food-odour detection^[6]. LC50 means the concentration associated with 50% mortality in that experiment. It is not a safe household target and cannot be copied across water chemistry, exposure time, product formulations or mixed invertebrates.

Before any treatment:

• identify the problem rather than medicating from one symptom;
• read the current product particulars and every invertebrate warning;
• check compatibility with all animals in the system;
• never improvise a half dose or mix treatments;
• obtain qualified advice when the diagnosis or product choice is unclear.

The VMD Product Information Database holds current information for authorised veterinary medicines in Great Britain and Northern Ireland^[11]. It does not make an unspecified aquarium remedy safe for shrimp. Follow the exact current label and professional direction where relevant.

Breeding: freshwater adults, saline larval development

Seeing eggs does not mean a freshwater colony will follow. C. multidentata is amphidromous: adults occupy freshwater, while larvae develop through a saline phase. In a controlled experiment, larvae completed development to juveniles across 17–34 ppt treatments under the study's particular temperature and culture conditions^[4]. OATA consequently describes Amano breeding as requiring a specialised brackish setup and specific larval food^[7].

This page deliberately gives no “set salinity to X on day Y” recipe. The research tested combinations under laboratory management; home water source, mixing accuracy, larval density, food culture, temperature and water quality can change the result. A community aquarium is not a controlled larval system.

An egg-carrying female can still be observed without treating her as a production project. Avoid unnecessary disturbance, keep the adult freshwater environment stable and understand that larval survival requires separate specialist planning.

Arrival, biosecurity and acclimation

Prepare the mature aquarium before purchase and ask the seller for measured holding temperature and water chemistry. Compare those values with your aquarium so that any transition is condition-led. There is no universal drip time that works for every journey, bag condition and water difference; follow the seller's current animal-specific arrival instructions.

Keep transport water out of the display where the seller's method advises, use dedicated wet equipment where practical and monitor new arrivals closely. Cefas professional guidance records water quality, health observations, movements and disinfection as core aquatic biosecurity controls^[14]. Those principles support careful separation and hygiene, but they do not create a universal household quarantine duration.

The cited English licensing guidance places environmental-conditions and water-quality advice in its fish section; it does not establish the same shrimp-specific statutory duty^[13]. Still ask the seller for current batch conditions before buying; measured information is more useful than an old generic dispatch promise.

Never release shrimp, aquarium water, plants or equipment contents into a pond, river or drain that can reach the wild. The GB Non-native Species Secretariat's pet code recommends secure rehoming or suitable disposal instead^[15].

Before you buy

• Confirm Caridina multidentata and ask what is known about the batch.
• Test the aquarium and confirm mature filtration, zero ammonia and zero nitrite.
• Start from OATA's approximate 20-litre and five-shrimp screens, then plan more space for fish and the full adult community.
• Compare the seller's measured water with yours and obtain current acclimation instructions.
• Protect filter intakes, close escape gaps and provide cover plus established surfaces.
• Plan appropriate food; do not buy shrimp as a guaranteed algae treatment.
• Screen every tank mate and retain a separation option.
• Check every medicine and treatment for invertebrate warnings before use.

For commercial intent, go to the Amano Shrimp shop page. For broader planning, continue with the freshwater shrimp guide, water chemistry guide, nitrogen-cycle guide and tank volume calculator.