Quick answer
Caridina multidentata, better known as the Amano shrimp, is a hardy freshwater shrimp kept mainly for algae control. Adults reach around 2 inches (5 cm), live roughly 2 to 3 years, and do well in temperatures of about 18 to 27°C (65 to 80°F) with a pH near 6.5 to 7.5. They need a mature tank with biofilm and algae to graze, a minimum of around 10 gallons, and absolutely no copper based medications. They will not successfully breed in a normal freshwater tank, because their larvae need brackish water to develop.
Caridina multidentata goes by several names, and that trips people up before they even start. Amano shrimp, Yamato shrimp, algae shrimp, and the older scientific name Caridina japonica all refer to the same animal.
I have kept them myself, though not currently. They are one of the few aquarium animals that genuinely earn their reputation, and also one that new keepers panic about more than they need to. This guide covers identification, care, feeding, breeding, and the problems people actually run into.
What is Caridina multidentata?
Caridina multidentata is a freshwater shrimp in the family Atyidae, native to Japan and Taiwan. It got its popular name from Takashi Amano, the aquascaper who used them for algae control in planted tanks.
Appearance. Translucent grey to light brown body with a row of dots and dashes along each side, and a pale stripe running down the back. The body is largely see through, which is why they can look ghostly against a dark substrate.
Size. Larger than most dwarf shrimp. Adults typically reach around 2 inches (5 cm), which is roughly double a cherry shrimp.
Lifespan. Around 2 to 3 years in a stable tank, sometimes longer.
Male vs female. The easiest tell is the row of markings along the side. Males have evenly spaced dots. Females have longer dashes rather than dots, and are noticeably larger and fuller bodied.
Caridina multidentata care and tank setup
They are hardy, which is why they are recommended so often, but hardy does not mean no requirements.
Tank size. Around 10 gallons minimum. They are active and larger than dwarf shrimp, and they need enough surface area to graze.
A mature tank. This is the requirement people skip. Amano shrimp feed on biofilm and algae, and a brand new tank has neither. Adding them to a tank that has been running a week is the most common reason they struggle. Wait until the tank has settled and surfaces have developed a film.
Water parameters. Temperature around 18 to 27°C (65 to 80°F). pH roughly 6.5 to 7.5. They tolerate a reasonable range, but stability matters more than hitting an exact number.
Substrate. They are not fussy. Sand or gravel both work, since they graze surfaces rather than digging.
Plants and hardscape. Plenty of cover matters. Moss, wood, and plants give them grazing surfaces and somewhere to hide, particularly after molting when they are soft and vulnerable.
Filtration. Use a sponge filter or a guard on the intake. Shrimp, especially smaller ones, get pulled into unguarded intakes.
Copper is the one hard rule. Copper is toxic to invertebrates. Check every medication, plant treatment, and fertiliser you dose for copper before it goes anywhere near a shrimp tank. This is the single fastest way to lose a whole colony.
What do Caridina multidentata eat?
They are grazers and scavengers, and they eat more or less constantly.
Algae. This is why most people buy them. They are genuinely effective on soft green algae and hair algae, which is where their reputation comes from.
Biofilm. The invisible microbial layer on surfaces in a mature tank. This is a staple food, and it is why a new sterile tank does not support them well. It is also the same white fuzzy biofilm that shows up on new driftwood, which shrimp will happily graze off.
Leftover food and decaying plant matter. They clean up what your fish miss.
Supplementary food. In a clean tank with little algae, they need feeding. Blanched vegetables like courgette or spinach, and prepared shrimp foods, both work. Feed sparingly.
On black beard algae specifically. This is the most over promised claim in the hobby. Amano shrimp will sometimes pick at black beard algae, particularly if there is little else available, but they are not a reliable cure for it. Buying shrimp to solve a BBA outbreak usually disappoints. Fix the underlying causes instead and treat any grazing as a bonus. I went through what actually works on BBA, and which animals genuinely eat it, in my black beard algae video → https://www.youtube.com/watch?v=ns1MQak59Rs
One honest caution. Hungry Amano shrimp can pick at soft new plant growth. It is not common in a well fed tank, but “they never touch plants” is an overstatement.
Tank mates
Generally safe: small peaceful community fish, other shrimp species, snails, and most small tetras and rasboras.
Risky: anything with a mouth big enough to eat a 2 inch shrimp. Larger cichlids, big gouramis, and most predatory fish will treat them as food.
Worth knowing: Amano shrimp are assertive feeders. They are fast, larger than dwarf shrimp, and will muscle in on food. In a tank with slower or shyer shrimp, make sure everyone actually gets fed.
Can Caridina multidentata breed in freshwater?
Practically speaking, no, and this surprises people who expect them to multiply like cherry shrimp.
Females carry eggs readily and you will often see a berried female in a healthy tank. The problem comes after hatching. Amano larvae need brackish water to develop, and in a normal freshwater aquarium they do not survive.
Breeding them deliberately means moving larvae to brackish water, raising them through their larval stages, then transitioning them back to freshwater. It is done, but it is a real project rather than something that happens on its own.
The practical takeaway: if you want a shrimp colony that breeds by itself, Neocaridina (cherry shrimp) are the answer. If you want algae control from an animal that will not overrun your tank, Amano shrimp are ideal precisely because they do not breed.
Common problems
Turning white or opaque. This causes more panic than anything else. A shrimp that has gone milky white and is not moving is usually dead or dying. But a completely clear, empty shrimp shaped shell is a moult, not a body, and that is entirely normal. Look for whether it is hollow before you assume the worst.
Molting problems. Shrimp shed their shell as they grow. A failed moult, where the shrimp gets stuck partway, is often linked to unstable water parameters, particularly sudden changes in mineral content during a water change. Slow, consistent water changes help more than any additive.
Hiding constantly. Normal for a while after being added, and normal right after molting, when they are soft and vulnerable. Persistent hiding in an established tank points at stress, poor water quality, or a tank mate bothering them.
Swimming frantically around the tank. Sometimes a male chasing a newly molted female, which is normal breeding behaviour. But sudden frantic swimming across the whole colony usually means a water quality problem, so test before assuming it is courtship.
Sudden deaths after a water change. Often a parameter swing, or something in the tap water. Shrimp are far more sensitive to abrupt changes than fish.
Caridina multidentata vs cherry shrimp
The two most common beginner shrimp, and they serve different purposes.
- Size: Amano shrimp are roughly twice the size of cherry shrimp
- Colour: Amanos are translucent grey, cherries are bright red
- Algae eating: Amanos are considerably more effective
- Breeding: cherries breed freely in freshwater, Amanos effectively do not
- Best for: Amanos for algae control in a planted tank, cherries for a self sustaining colourful colony
Many planted tank keepers run both.
Mistakes to avoid
Adding them to a brand new tank. No biofilm, no algae, nothing to eat. Wait until the tank has matured.
Using any copper containing treatment. Check every product label. This kills invertebrates.
Expecting them to fix black beard algae. They are not a reliable solution for it.
Assuming every white shrimp is dead. Check whether it is a hollow moult first.
Buying too few. They are more relaxed and more active in a small group rather than as a single individual.
Unguarded filter intakes. An easy and avoidable loss.
Signs of a healthy Amano shrimp
Most of this guide covers what goes wrong, so here is what right looks like. If you are watching your tank and wondering whether your shrimp are doing well, these are the things to check.
Constant grazing. A healthy Amano shrimp is almost always busy, picking over plants, wood, and glass with its front legs. Shrimp that sit still for long stretches are worth watching.
A clear, translucent body. Grey brown and see through, with the dot and dash markings visible along the sides. Cloudiness or a milky white tone is a warning sign.
Regular successful moults. Finding empty, hollow shells around the tank is a good sign, not a bad one. It means they are growing and shedding cleanly.
A good appetite. They should come out when food goes in, and they should be assertive about it. Amano shrimp are not shy eaters.
Alert, responsive behaviour. They react to movement and to food, and they move purposefully rather than drifting.
Berried females, if mature. A female carrying eggs under her tail means she is mature and conditions are good. The eggs will not hatch into surviving shrimp in freshwater, but seeing them is still a sign of a healthy, well fed animal.
Using cover normally. Hiding right after a moult is normal and healthy, since they are soft and vulnerable for a day or two. Hiding constantly in an established tank is not.
FAQ
What is Caridina multidentata? It is a freshwater shrimp native to Japan and Taiwan, commonly sold as the Amano shrimp or Yamato shrimp, and kept mainly for algae control in planted aquariums. It was previously known as Caridina japonica.
How big do Caridina multidentata get? Adults typically reach around 2 inches (5 cm), which makes them roughly twice the size of cherry shrimp.
How long do Amano shrimp live? Around 2 to 3 years in a stable, mature tank, sometimes longer.
What water parameters do Caridina multidentata need? Roughly 18 to 27°C (65 to 80°F) and a pH around 6.5 to 7.5. Stability matters more than exact numbers, and copper based products must be avoided entirely.
Can Caridina multidentata breed in freshwater? Not successfully. Females carry eggs, but the larvae require brackish water to develop, so they do not survive in a normal freshwater aquarium.
Do Caridina multidentata eat black beard algae? Sometimes, but not reliably. They are effective on soft green and hair algae. Buying them specifically to clear black beard algae usually disappoints.
How do you tell male from female Caridina multidentata? Look at the markings along the side. Males have evenly spaced dots, while females have longer dashes and are larger and fuller bodied.
Why is my Amano shrimp turning white? A milky white, motionless shrimp is usually dying. A clear, hollow, shrimp shaped shell is a normal moult. Check whether it is empty before assuming the worst.
How many Amano shrimp per gallon? A common guideline is around one shrimp per 2 gallons, adjusted for how much algae and biofilm your tank actually supports.
Final word
Caridina multidentata is one of the genuinely useful animals in the hobby. Hardy, effective on algae, and it will not overrun your tank because it cannot breed in freshwater.
Give them a mature tank with something to graze, keep parameters stable rather than perfect, guard your filter intake, and keep every trace of copper away from them. Most Amano shrimp problems trace back to one of those four things.
And before you panic over a white shrimp, check whether it is hollow. More often than not, it is just a moult.
