Amano Shrimp Care Guide: The Ultimate Algae Eater for Planted Tanks

Amano shrimp (Caridina multidentata) are the workhorse algae eater of the freshwater hobby. Larger and faster than the dwarf Neocaridina species, they spend their entire day picking through plants, driftwood, and substrate, scraping off the soft green algae and biofilm that fish leave behind. Takashi Amano — the late Japanese aquascaper who pioneered the modern planted-tank style — used them by the dozen in his iconic Nature Aquarium displays, and the species has carried his name in the hobby ever since. They are clear-bodied, peaceful, and almost impossible to kill once acclimated, but they have one quirk that sets them apart from every other shrimp on the market: every Amano you buy was caught in the wild, because they cannot reproduce in freshwater.

Species Overview#

Amano shrimp are native to the streams and rivers of Japan, Taiwan, and parts of Korea, where adults live in pure freshwater and migrate downstream to release their larvae into brackish estuaries. Adult shrimp are translucent gray to olive-tan with a row of distinct dotted or dashed markings running along each flank — the dot pattern is one of the easiest field IDs for a true Caridina multidentata. They reach roughly 2 inches at full size, considerably larger than Cherry shrimp, with the females growing slightly bigger and showing more pronounced dot rows than the males.

The species was popularized in the West in the late 1980s after Takashi Amano began featuring them as the algae-control workhorse in his Aqua Design Amano (ADA) displays. He reportedly ordered them by the thousand to clear hair algae from his iconic planted scapes, and the trade name "Amano shrimp" stuck with hobbyists outside Japan, where they had been called Yamato numa-ebi for decades. Today every reputable freshwater retailer carries them as a standard offering for planted-tank keepers.

Adult size

2 in (5 cm)

Lifespan

2-5 years

Min tank

10 gallons

Temperament

Peaceful

Difficulty

Intermediate

Diet

Omnivore (algae grazer)

The Legacy of Takashi Amano and the "Yamato Shrimp"#

Takashi Amano (1954-2015) was the Japanese photographer, designer, and aquarist who effectively invented the modern planted-tank aesthetic. He founded Aqua Design Amano in 1982, and his Nature Aquarium style — built around iwagumi rockscapes, carpeting plants, and meticulously tuned light, CO2, and nutrient regimes — defined what a "show tank" looks like for a generation of hobbyists. He died in 2015, but ADA still produces the substrate, lighting, and filtration gear that bears his name.

What made Amano famous in shrimp circles was a single practical decision: he needed a creature that would eat the hair algae and threadlike growth that plagued his high-light, high-nutrient tanks without disturbing the plants or harassing his fish. He landed on Caridina multidentata, a species locally common in the streams near his home prefecture of Niigata, and started using them at densities of 50-100 per display tank. The English-speaking hobby renamed the species "Amano shrimp" in his honor sometime in the early 1990s, and the name has stuck.

Many serious aquascapers consider Amanos the best algae-eater in the freshwater hobby — the consensus echoes Amano's own claim. They will not solve every algae problem (nothing does), but a well-fed group of Amanos in a properly stocked tank will keep most soft green and hair algae in check without you ever needing to dose chemical algaecides.

Identifying Caridina multidentata vs. "False" Amanos#

True Amano shrimp are translucent gray-tan with a clear lateral stripe along the back and a distinct row of dotted or dashed markings — sometimes called the "Morse code" pattern — running along each side from the head to the tail. The dots are reddish-brown to olive depending on the individual and the diet. Males show smaller, more uniform dots; females show larger, more elongated dashes that may merge into short bars. Both sexes have completely transparent legs, antennae, and tail fans — there is no opaque pigmentation anywhere on a true Amano.

Several lookalike species are sold as "Amano shrimp" in big-box pet retailers and lower-end online vendors. The most common imposter is Caridina serrata and various unidentified Asian Caridina species that are smaller, paler, and lack the distinct dot pattern. They often die within weeks because the conditions that suit C. multidentata do not always suit the substitute species. If the shrimp in the tank look uniformly pale, lack the lateral dot row, or appear noticeably smaller than 1.5 inches, you may be looking at a false Amano.

A second tell is behavior. True Amanos are active, almost frenetic foragers — they swim in short bursts, climb plants and decor constantly, and rarely sit still for more than a minute. Lethargic shrimp clinging to one spot in the tank are either stressed from a recent shipment or are not the species advertised. When in doubt, ask the seller for the scientific name in writing before buying.

Maximum Size (2 inches) and Lifespan (2-5 years)#

A healthy adult Amano reaches 1.75 to 2 inches (about 5 cm), with females consistently larger than males. They are roughly twice the size of an adult Cherry shrimp and noticeably bulkier through the abdomen. This size difference matters operationally — a 2-inch shrimp can outcompete a Cherry at feeding time, can muscle past most small fish for sinking pellets, and is too big for the average 1-inch tetra or rasbora to consider eating.

Lifespan in well-maintained freshwater tanks runs 2-5 years, considerably longer than the 1-2 year ceiling on Neocaridina. Many keepers report individuals living past 4 years on stable water and a varied diet. Because Amanos do not reproduce in freshwater, your starting group is your final group — you will not see colony growth the way you do with Cherries. Plan your initial purchase for the population you want long term, factoring in slow attrition from molting failures and the occasional escape.

Most premature deaths trace to one of three things: copper exposure, ammonia spikes from an under-cycled tank, or molting complications from inadequate GH. Once an Amano has lived through its first month in your tank, it has cleared the highest-risk window and is statistically likely to live out its full lifespan.

Water Parameters & Tank Requirements#

Amanos tolerate a wider parameter range than most aquarium shrimp, which is part of why they survive the brutal supply chain that brings them from Asian streams to your tank. They will live in everything from soft tropical water to moderately hard temperate water, and they handle small parameter swings better than dwarf Neocaridina species. Stability still beats precision, but the window of acceptable conditions is meaningfully larger than for Cherries.

Ideal Temperature (70°F-80°F) and pH (6.5-7.5)#

Target a temperature of 70-78 F, with 72-76 F being the sweet spot for activity, feeding, and molting. They survive temperatures in the low 80s for short periods, but sustained heat above 80 F suppresses appetite, accelerates molting cycles, and shortens lifespan. Most keepers run a standard adjustable heater set to 74 F and never think about it again.

Aim for pH in the 6.5-7.5 range. Amanos handle slightly acidic to mildly alkaline water without complaint, which is why they slot into so many community planted tanks where CO2 injection drives pH down into the low 6s during the day. General hardness should be 4-12 dGH — they need dissolved calcium and magnesium for molting, but they are far less picky about exact GH than Cherry or Crystal shrimp. Carbonate hardness of 2-8 dKH gives the tank enough buffering capacity to ride out small pH swings.

Ammonia and nitrite must read zero. Amanos are more tolerant of nitrate than dwarf shrimp, but keep nitrates under 20 ppm with weekly water changes for best long-term health. The single most common parameter-related death in this species is chronic nitrate creep in tanks that go too long between water changes — the shrimp survive for months, then start dying off in their second year for no apparent reason. Test nitrates monthly even in a tank that looks clean.

Minimum Tank Size: Why 10 Gallons is the Sweet Spot#

A 10-gallon tank is the practical minimum for a small group of 3-5 Amanos. Smaller tanks experience faster temperature and pH swings, which Amanos handle better than Cherries but still do not love. A 10-gallon also gives you enough swimming surface and grazing area that a group of 5 will not run out of biofilm and algae between feedings. Most keepers settle on 15-29 gallons for a serious algae-control crew of 6-10 shrimp.

The often-quoted stocking rule is 1 shrimp per 2-5 gallons. That number assumes they are doing real work as algae eaters in a planted tank with light fish stocking and visible algae growth. In a sterile, high-flow, fish-heavy tank with little biofilm, that ratio drops to 1 per 5+ gallons because there is simply not enough food to support a denser population without daily supplemental feeding.

A 20-gallon long is arguably the ideal Amano tank. The footprint gives them more substrate to forage on than a tall tank of equal volume, and the larger water column buffers parameter swings. Six to eight Amanos in a 20-long with moderate plant coverage will keep most algae problems at bay without any chemical intervention.

Filtration and Oxygenation: Managing High Bio-loads#

Amanos tolerate a wide range of filtration setups. Sponge filters work well for shrimp-only or low-stocking tanks because they cannot suck in adults, and they cultivate the biofilm that Amanos graze on. Hang-on-back and canister filters are fine for community tanks, but cover the intake with a fine sponge pre-filter — adult Amanos are too large to be sucked in, but the prefilter still catches detritus they will graze on later, and it protects any small fry from any community fish that happen to spawn.

Oxygenation matters more for Amanos than for Cherries. They are larger, more active, and pull more dissolved oxygen out of the water column on a per-shrimp basis. In a heavily planted tank with CO2 injection, ensure you have surface agitation overnight when plants stop producing oxygen and start consuming it. A small air stone or a slightly raised filter outlet is usually enough. Low oxygen is one of the documented triggers for Amanos climbing out of the tank — see the FAQ section on that behavior below.

A tight-fitting lid is non-negotiable. Amanos are notorious escape artists, and a tank without a glass top or fine mesh covering will lose shrimp to the floor over time. Cover even the small gaps around heater cords and filter intakes — these are the most common escape routes.

Diet & Feeding#

Amanos earn their keep as algae eaters, and a well-stocked tank with established biofilm and visible algae will sustain a group of 5-8 with minimal supplemental feeding. That said, they are omnivorous opportunists who will eagerly eat almost anything you put in the tank, and a varied diet supports healthier molts and longer lifespans.

The Algae Menu: Hair Algae, Brush Algae, and Biofilm#

Amanos preferentially eat soft green algae, hair algae, fuzz algae, and biofilm — the films and threads that coat hardscape, glass, and slow-growing plants. They will also work on diatoms (brown algae) in newly cycled tanks, and they can be coaxed into eating black brush algae (BBA) if other food sources are limited. They generally do not touch green spot algae or stubborn green dust algae on glass.

A single Amano is a remarkably efficient grazer compared to a Cherry. They cover more ground, climb higher, and have larger mandibles that can scrape tougher growth. A group of 6-8 Amanos in a 20-gallon tank with a moderate algae problem will typically clear visible hair algae within 1-2 weeks. The catch is that once the algae is gone, you need to feed them — they do not stop eating just because the buffet is closed.

For tanks struggling with brown diatoms specifically, see our guide on brown algae in fish tanks — Amanos will help, but the underlying silicate and lighting issues need to be addressed too.

Supplemental Feeding: Bacter AE, Pellets, and Blanched Veggies#

Once the visible algae is under control, feed supplemental food 2-3 times per week. Algae wafers and shrimp pellets from brands like Hikari, Shrimp King, and GlasGarten are the standard staple. A single algae wafer split between 5-8 shrimp is plenty for a feeding. Blanched zucchini, spinach, kale, and cucumber slices work as inexpensive vegetable supplements — blanch for 30-60 seconds in boiling water, cool, and drop a small piece into the tank. Remove any uneaten portion after 12-24 hours.

Bacter AE and similar powdered supplements seed the tank with biofilm-promoting bacteria and provide a fine particulate food that Amanos will pick up off surfaces. A pinch dosed once or twice weekly supports natural grazing and benefits any other inverts in the tank. These powders are especially useful in newer tanks where biofilm has not fully established.

Avoid feeding heavy protein every day. High-protein foods like bloodworms can be offered occasionally as a treat, but a steady high-protein diet promotes rapid growth that can lead to molting complications. Variety is the goal — rotate two or three product types and supplement with vegetables.

Copper Sensitivity and Vitamin Requirements for Molting#

Copper-free fertilizers are essential. Most major planted-tank fertilizer brands now offer "shrimp-safe" or copper-free versions of their products — read the label specifically. Some all-in-one fertilizers contain trace copper as a plant micronutrient; these will slowly poison your Amano colony if dosed long-term.

Calcium and magnesium are critical for molting. Amanos rebuild their entire exoskeleton (made of chitin reinforced with calcium carbonate) every 4-8 weeks throughout their lives. If your GH is below 4 or your tank lacks dissolved minerals, molts can fail catastrophically. In soft-water regions, supplement with a shrimp-specific GH booster or place a small amount of crushed coral in the filter to keep mineral content stable.

Tank Mates & Compatibility#

Amanos are large enough to ignore most community fish that would happily eat a Cherry shrimp. Their 2-inch adult size puts them outside the prey window of small tetras, rasboras, and most peaceful community fish. They are not invulnerable — large cichlids and goldfish will still eat them — but the realistic safe tank-mate list is much wider than for dwarf shrimp.

Best Community Partners: Tetras, Rasboras, and Corydoras#

The classic Amano community pairs are small to mid-sized peaceful fish: neon tetras, ember tetras, cardinal tetras, harlequin rasboras, chili rasboras, and any of the smaller Boraras species. Pygmy and standard corydoras are excellent companions because they share a substrate-foraging lifestyle without competing for the same surface algae. Otocinclus catfish and Amanos are a textbook pairing — both species clean different parts of the tank and ignore each other entirely.

Honey gouramis, sparkling gouramis, and most peaceful rainbowfish work well too. Just-add-water shrimp tanks often include a small school of 6-10 chili rasboras alongside 8 Amanos in a 20-gallon long, and the combination is one of the most popular nano planted-tank stocking plans in the hobby. For more on compatible freshwater community fish, see our freshwater fish guide.

The single rule that matters: nothing with a mouth bigger than the shrimp's body, and nothing aggressive enough to harass them during their vulnerable post-molt window. Even normally peaceful fish will sometimes opportunistically eat a freshly molted shrimp, which is why dense plant cover (Java moss, Christmas moss, subwassertang) is essential.

Dangerous Roommates: Cichlids, Goldfish, and Large Barbs#

Avoid keeping Amanos with any cichlid larger than a small ram, all goldfish (which are large enough to swallow adult Amanos whole), large barbs (tinfoil, rosy, tiger), all loaches larger than kuhlis, and any predatory fish like pufferfish, archers, or knife fish. Crayfish and most freshwater crabs will also kill Amanos. Even some "peaceful" gouramis like blue or pearl will harass and pick at them — stick to honey or sparkling gouramis if you want to mix the families.

Bettas are a case-by-case decision. Most bettas leave a 2-inch Amano alone because the shrimp is too large to eat in one bite, but individual betta temperament varies wildly. If you try the combination, start with a fully grown Amano (not juveniles), provide dense moss cover, and watch for signs of harassment. Fin-flaring at the shrimp is fine; sustained chasing is not.

Keeping Amanos with Cherry Shrimp (Neocaridina)#

In display tanks where you do not care about Cherry colony growth, the two species look fine together — the translucent Amano contrasts visually with the bright red Cherry, and they fill different ecological roles (Amano as primary algae eater, Cherry as biofilm grazer and detritus cleaner). Just understand that the Cherry colony will grow more slowly than it would in a dedicated tank.

For comparison shopping between species, see our cherry shrimp care guide and the dedicated red cherry shrimp species page. Ghost shrimp are another commonly considered alternative — see the ghost shrimp care guide for that species' specific tradeoffs.

The Breeding Challenge#

If you want a self-sustaining shrimp colony, do not buy Amanos. They are physiologically incapable of completing their reproductive cycle in freshwater, and the breeding setup required to coax them through the larval stage is so demanding that essentially no one in the hobby does it commercially. This is the single biggest practical difference between Amanos and Neocaridina species.

Why Amano Shrimp Won't Breed in Freshwater#

Female Amanos will become berried in a freshwater tank — the bright green clutch of eggs is visible under the tail just like in any other shrimp species. The eggs will develop normally, and the female will fan them on her swimmerets for the standard 30-40 day incubation period. The problem starts the moment they hatch.

Amano larvae are not miniature adults the way Cherry shrimplets are. They are tiny planktonic zoea, less than a millimeter long, that must drift through brackish or saltwater for the first 30-50 days of life before metamorphosing into recognizable juvenile shrimp. In pure freshwater, the larvae cannot regulate their internal salt levels and die within 3-5 days of hatching. There is no workaround for this in a standard freshwater tank.

The Complex Larval Cycle: Transitioning to Brackish Water#

A handful of dedicated shrimp keepers and some commercial operations in Japan and Taiwan have managed to breed Amanos in captivity, but the process requires a complex multi-tank setup. Berried females are kept in freshwater until just before hatching. Newly hatched zoea are immediately transferred to a saltwater or brackish nursery tank with a specific gravity around 1.018-1.024, fed a specialized diet of phytoplankton and infusoria, and gradually transitioned back to freshwater over the course of 30-60 days as they metamorphose. Mortality is high, growth is slow, and the labor involved makes wild-caught imports far cheaper.

This is why every Amano shrimp on the retail market is wild-caught from streams in Japan, Taiwan, or Korea. It also explains why prices stay relatively stable around $4-$8 per shrimp despite huge demand — there is no captive-bred fallback supply, so prices reflect collection and shipping logistics rather than breeder economics.

Common Health Issues#

Most Amano deaths in home tanks come from one of three causes: failed molts, bacterial infection, or acclimation shock from poor handling at the point of sale. None of the three are difficult to prevent if you know what to look for.

Molting Failures and the "White Ring of Death"#

Amanos molt every 4-8 weeks throughout their lives. A successful molt produces a full ghost-like exoskeleton shed that will float around the tank for a day or two — do not remove it, the shrimp eat it for the calcium. A failed molt produces a visible white ring or band around the shrimp's midsection where the old shell has cracked but the new shell underneath has not calcified properly. The shrimp typically cannot complete the molt and dies within 24-48 hours.

The primary cause is insufficient mineral content (GH below 4) or sudden parameter swings during the molting window. Maintain GH at 6-10 dGH and avoid large water changes when shrimp are visibly close to molting. In soft-water regions, a small amount of crushed coral in the filter or a dedicated GH booster keeps mineral levels stable. Iodine supplements are sometimes recommended but the evidence for their necessity in Caridina multidentata specifically is mixed — focus on calcium and magnesium first.

Muscular Necrosis and Bacterial Infections#

Muscular necrosis presents as a milky or opaque white discoloration in the abdomen muscle visible through the translucent shell. It is bacterial in origin, often triggered by poor water quality, chronic ammonia exposure, or the stress of recent shipping. Once the white opacity is visible, the prognosis is poor — treatment with shrimp-safe antibiotics is rarely effective at the home-tank scale.

Prevention is the only reliable strategy. Keep ammonia and nitrite at zero, nitrates below 20 ppm, and avoid large parameter swings. Quarantine new shrimp for 1-2 weeks in a small cycled tank before adding them to your main display — this catches infections before they spread. If a single shrimp shows signs of necrosis, remove it from the tank to prevent any infectious spread to the rest of the colony.

Bacterial infections more broadly can present as pink or orange discoloration in internal tissue, lethargy with loss of appetite, or unusual surface clinging behavior. The treatment is the same: improve water quality, reduce stress, and isolate affected individuals.

Acclimation Stress: The Drip Method Importance#

Amanos are wild-caught and have already endured a brutal supply chain by the time they reach your local fish store — they were collected in Asia, shipped to a wholesaler, distributed to a retailer, and finally moved to a tank with parameters that may bear no resemblance to the stream they came from. Adding them directly to your tank without slow acclimation regularly kills shipments outright.

Drip acclimate every Amano shrimp over 1-2 hours minimum. Float the bag for 15 minutes to match temperature, then transfer the shrimp and bag water to a separate container and use airline tubing tied in a loose knot to drip tank water into the container at a rate of 2-4 drops per second. After 90-120 minutes, the container water should be roughly 75% your tank's parameters. Net the shrimp into the tank — do not pour the bag water in, since it may carry parasites or copper traces from the supply chain.

The first 48 hours after introduction are the highest-risk window. Avoid doing anything that disturbs the shrimp during this period — no cleaning, no rearranging decor, minimal lighting. Losses in the first week are common and usually trace to parameter shock during the original wholesale handling, not to your tank conditions.

Where to Buy & What to Look For#

Sourcing healthy Amanos matters more than for almost any other shrimp species, because their wild-caught supply chain means you are inheriting whatever stress and damage occurred during collection and shipping. A good local fish store stages Amanos for 1-2 weeks after delivery before selling them, which gives the shrimp time to recover and lets the staff cull any obvious losses.

Sourcing from Local Fish Stores (LFS) vs. Online#

Local fish stores are usually the better choice for Amanos. You can inspect the shrimp in person, see the tank conditions they have been stored in, and confirm they have been on-site long enough to have shed their shipping stress. A reputable LFS will hold incoming Amanos in a quarantine tank for at least a week before putting them on the sales floor — ask the staff about their handling protocol before buying.

Online sellers can work, but the shipping itself adds another stress event to an already stressed animal. If you order online, choose a seller who guarantees live arrival, ships overnight or next-day with appropriate insulation, and stages the shrimp in their own tanks for at least 7 days before shipping. Avoid the ultra-cheap "10 Amanos for $20 with free shipping" listings on general marketplaces — the bulk-shipping economics behind those listings almost always sacrifice survival rate.

Signs of a Healthy Shrimp: Activity Levels and Coloration#

Healthy Amanos are constantly moving. They climb plants, swim short bursts between rocks and decor, and pick at surfaces continuously. A shrimp clinging motionless to one spot is either freshly arrived (give it a few days) or stressed enough that you should not buy it. Activity is the single best one-shot health indicator.

Look for the distinctive lateral dot pattern visible on both flanks. The dots should be clearly defined and uniform in color — reddish-brown to olive. Shrimp with washed-out, faded, or absent dots may be stressed, malnourished, or one of the false-Amano substitute species. All ten legs and both pairs of antennae should be intact; missing appendages indicate aggressive tank mates, recent failed molts, or poor handling.

Avoid any shrimp showing milky white opacity in the body, white rings around the midsection, pink or red internal discoloration, or unusual surface-clinging behavior. Avoid tanks with visible dead shrimp in them. If the seller cannot net the specific shrimp you point to without stressing the rest of the tank, that is also a sign that the staff lacks experience with the species.

Quick Reference#

• Tank size: 10 gallons minimum, 20-gallon long ideal for a group of 6-8
• Temperature: 70-78 F (21-26 C); 74 F is the sweet spot
• pH: 6.5-7.5
• GH: 6-10 dGH (critical for molting)
• KH: 2-8 dKH
• Ammonia / Nitrite: 0 ppm (always)
• Nitrate: Under 20 ppm — test monthly
• Adult size: 2 inches (5 cm); females larger than males
• Lifespan: 2-5 years in stable freshwater
• Stocking: 1 shrimp per 2-5 gallons in a planted tank
• Filtration: Sponge filter, HOB, or canister with intake guard
• Lid: Tight-fitting, all gaps sealed (Amanos escape)
• Diet: Algae grazer; supplement 2-3x weekly with wafers, pellets, blanched vegetables
• Breeding: Not possible in freshwater — larvae need brackish water
• Safe tank mates: Small tetras, rasboras, corydoras, otocinclus, honey gouramis
• Avoid: Cichlids, goldfish, large barbs, loaches, crayfish, pufferfish
• Never use: Copper-containing medications, fertilizers with copper sulfate, uncycled tanks
• Acclimation: Drip acclimate over 90-120 minutes; never pour bag water into the tank
• Difficulty: Intermediate — wild-caught only, requires careful sourcing and acclimation