Amano Shrimp

Caridina multidentata

Also known as: Yamato shrimp, Algae-eating shrimp, Japanese shrimp

Water Parameters

• Temperature: 20–27°C
• pH: 6.5–8
• Hardness (GH): 71–250 ppm (4–14 dGH)

Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.

Care Summary

The single most effective algae-eating shrimp in the hobby, with a working appetite far exceeding their size. Will systematically clear soft green algae, hair algae, and most other unwanted growth from a planted tank. Their translucent body with scattered brown spots makes them less visually striking than cherry shrimp but more functionally useful. Particularly sensitive to copper (as with all shrimp), so avoid all copper-based medications and check that any plant fertilisers are shrimp-safe. Often kept in groups of 3-6 in larger tanks for algae control rather than as a centrepiece species. They are adaptable but need minerals to moult well: keep a moderate carbonate hardness (KH) and GH, and avoid very soft, near-zero-KH water, which leads to moulting problems.

Behaviour and Temperament

Amano shrimp are daytime foragers, and that is the main behavioural difference between them and cherry shrimp. Where Neocaridina tend to graze in cover and scatter when disturbed, amano shrimp work in the open, walking over leaves, wood, and glass in plain view for most of the day. If you want to actually see your clean-up crew, this is the species that obliges.

They are not schooling animals, but they are noticeably calmer in a group of three or more. Kept singly, an amano shrimp tends to stay hidden. In a group they spread out and forage confidently. You will occasionally see a larger individual chase a smaller one off a piece of food, sometimes dragging a wafer away to eat in private. This is normal competition, not aggression, and no damage results.

Every few weeks each shrimp moults, shedding its exoskeleton whole. The discarded shell is translucent white and holds its shape, so new keepers regularly mistake it for a dead shrimp. Leave it in the tank. The shrimp eat the moult back to recover the minerals in it, and a shrimp that has just moulted will hide for a day or two while its new shell hardens.

One practical quirk: amano shrimp climb. They will walk up airline tubing, filter intakes, and heater cords, and they are notably prone to leaving the tank when water quality drops. A lid, or at minimum covered cable and pipe entry points, prevents finding a dried shrimp on the floor behind the cabinet.

Tank and Water Setup

The 38 litre (10 gallon) minimum is about food supply rather than swimming space. A group of three to six shrimp will strip a smaller nano tank of algae and biofilm within weeks, after which you are hand-feeding them permanently. A mature, planted tank with some surface area for biofilm to develop is what keeps them genuinely self-sufficient.

Do not add amano shrimp to a freshly cycled tank. They are markedly more sensitive to ammonia and nitrite than most community fish, and a tank that has only just finished cycling has neither stable parameters nor anything for them to eat. Wait until the tank has been running for six to eight weeks and has visible biofilm and some soft algae growth.

Water hardness is where Australian keepers most often get this species wrong. Amano shrimp need a general hardness of at least 71 ppm (about 4 dGH) to moult reliably, and they need carbonate hardness alongside it. Melbourne tap water runs roughly 8 to 31 ppm, and Sydney sits around 51 ppm. Both are well below the minimum, and both are poorly buffered. Used untreated, that soft water is the single most common cause of moulting failure in southern Australian shrimp tanks. Remineralise with a GH and KH booster to bring the tank into range before the shrimp go in. Brisbane at roughly 121 ppm and Adelaide at 108 ppm are comfortably suitable as they come from the tap. Perth depends entirely on your suburb: the Dwellingup end of the network at 29 ppm needs remineralising, while the northern limestone corridor around Two Rocks at 228 ppm does not. See the water parameters guide for the full profiles, and the hardness converter to move between ppm and dGH.

Copper is the other absolute. Amano shrimp are killed by copper at concentrations well below the dose used to treat fish disease, so no copper-based medication can be used in a tank containing them, and any plant fertiliser needs checking for copper content before it goes in. If a fish in the tank needs copper treatment, the fish moves to a hospital tank, not the other way around.

For dechlorinator, use one rated for chloramine as well as chlorine. Seachem Prime covers both, which matters in Sydney and Brisbane where the supply is chloraminated and chloramine will not gas off from standing water. On temperature, the 20 to 27°C range sounds forgiving, but an unheated tank in Melbourne, Adelaide, or Hobart will fall below 20°C over winter, so a heater is still needed in the southern states.

Feeding

Algae comes first, and for the first month or two in a mature tank it will be the whole diet. The problem arrives afterwards. A group of amano shrimp is efficient enough to eliminate the visible algae in a well-lit planted tank, at which point their food supply disappears and most keepers do not notice until the shrimp are visibly thin.

Once the tank is clean, supplement two or three times a week rather than daily. Blanched zucchini or spinach, sinking algae wafers, and shrimp-specific foods all work. Feed a small amount and remove anything uneaten after a few hours. The useful warning sign is behavioural: shrimp that spend their time massed on the front glass rather than foraging across the tank are telling you the tank has run out of food.

Minerals matter more than protein for this species. Calcium and carbonate go into every new shell, and a shrimp that is eating well but living in soft, poorly buffered water will still moult badly. Diet and water hardness are two halves of the same problem, which is why a failed moult so often traces back to the tap rather than the food.

Tankmates

Significantly larger than cherry shrimp; adults are too big to be threatened by most peaceful community fish, including most tetras, rasboras, and corydoras. Unlike Neocaridina shrimp, amano shrimp cannot breed in freshwater (their larvae require brackish water), so they will never overpopulate a tank. Made famous by aquascaper Takashi Amano as the best natural algae control for planted tanks. Active foragers visible throughout the day.

Compatible with

• Neon Tetra
• Harlequin Rasbora
• Bronze Corydoras
• Ember Tetra
• White Cloud Mountain Minnow
• Otocinclus
• Mystery Snail

Avoid keeping with

• Betta
• Angelfish
• Large Cichlids
• Loaches
• Assassin Snail
• Tiger Barb
• Electric Yellow Cichlid

Breeding

For practical purposes, amano shrimp will not breed in a home freshwater tank, and this is a feature rather than a fault. Females berry readily and you will see a mature female carrying a dense clutch of eggs under her tail on a regular basis. The eggs hatch into free-swimming larvae called zoeae, and those larvae require brackish water to develop. In fresh water they survive only a few days.

Deliberate breeding is possible but genuinely difficult. It requires a separate larval tank at marine or near-marine salinity, a continuous supply of cultured algae small enough for the larvae to eat, and a gradual return to fresh water over several weeks as they metamorphose. Very few hobbyists attempt it and fewer complete it.

The consequence worth planning for is that a colony never becomes self-sustaining. Unlike cherry shrimp, which will fill a tank given time, an amano population only shrinks. With a two to three year lifespan, expect to replace the group periodically rather than treating the initial purchase as permanent.

Common Problems

• copper poisoning from medications or plant fertilisers
• moulting failure from inadequate diet or sudden parameter shifts
• predation by aggressive fish
• ammonia spike sensitivity in newly cycled tanks

Common Mistakes

• Adding them to a newly cycled tank, where ammonia sensitivity and a total absence of biofilm combine to kill them within weeks.
• Using Melbourne or Sydney tap water untreated. Both are below the 71 ppm hardness minimum and cause moulting failure.
• Treating the tank with a copper-based medication, or adding a plant fertiliser without checking it for copper.
• Buying one or two rather than a group of three or more, which produces a shrimp that hides permanently and is rarely seen again.
• Expecting the colony to replace itself. The larvae cannot survive in fresh water, so the group needs periodic restocking.
• Adding them to fix an algae problem without addressing its cause. Excess light or nutrients will outpace any number of shrimp.
• Running an open-topped tank, given how readily this species climbs cables and pipework and leaves.

Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-08-01