Amano Shrimp Caridina multidentata

Quick Stats

Tank Setup

The Amano Shrimp (Caridina multidentata, formerly Caridina japonica) is the algae-eating workhorse of the freshwater hobby. They are roughly twice the size of an adult Cherry Shrimp, far more active during the day, and aggressively curious about anything that looks like food. The species was popularised by Takashi Amano — the famous Japanese aquascaper whose name they now carry — who put them in virtually every Nature Aquarium layout he photographed because no other invertebrate cleans as thoroughly. A 10 gallon tank is the floor for a group of 3–5; a 20 gallon planted is the realistic sweet spot.

Water parameters: temperature 18–28°C, pH 6.0–7.5, hardness 4–10 dGH. That range covers almost any dechlorinated tap water. They tolerate slightly warmer water than Cherry Shrimp (up to 28°C sustained, vs 26°C for cherries) and slightly softer, more acidic conditions. I keep mine at 24°C, pH 7.0, GH 6 in a planted 20 gallon — the same water my Ember Tetras and Pygmy Corydoras live in — and they breed (well, attempt to breed; see below) and thrive. Stability matters more than hitting specific numbers; shrimp in general are far more sensitive to parameter swings than fish.

Set up the tank with sand or fine gravel substrate, driftwood, and plenty of plants — Amanos spend their day patrolling plant leaves and wood surfaces grazing on algae and biofilm. They are larger and heavier than Neocaridina, so they will uproot stem plants that are not well-rooted; plant in baskets or weight the stems until they take hold. A sponge filter is ideal, but a hang-on-back with a pre-filter sponge on the intake also works. Like all shrimp, they are sensitive to copper — use only shrimp-safe plant fertilisers and never dose copper-based medications in their tank.

Tank Mates

Amano Shrimp are peaceful and largely defenseless as adults — though at 5–6 cm they are too big for most small community fish to swallow whole. The risk is the inverse: a single large fish (a full-grown angelfish, a goldfish, a 10 cm cichlid) will harass and eventually eat an Amano. The other risk is that Amanos are opportunistic — a hungry adult Amano will catch and eat a Cherry Shrimp shrimplet or a small snail, and may grab a slow-moving fish fry.

Compatible tank mates: Cherry Shrimp, Crystal Red Shrimp, snails (Nerite, Mystery, Ramshorn, Malaysian Trumpet), small peaceful community fish (Ember Tetras, Pygmy Corydoras, Otocinclus, Chili Rasboras, Celestial Pearl Danios), small pencil fish, and dwarf cichlids like Apistogramma. Amanos also pair well with small schooling tetras in planted tanks — this is exactly the combination Takashi Amano used in his Nature Aquarium layouts. Avoid any fish large enough to swallow a 5 cm shrimp whole (goldfish, large cichlids, big barbs) and avoid loaches, which hunt shrimp.

Group size matters less than with Cherry Shrimp because Amanos do not form colonies that breed in the tank — you are buying a work crew, not a breeding stock. Three is the floor; five is comfortable for a 20 gallon; ten in a heavily planted 40 gallon is a genuine algae-control team. Amanos are somewhat social and will forage in loose groups when food is abundant, but they do not school or shoal. Single Amanos do fine but spend more time hiding.

Diet & Feeding

Amano Shrimp are omnivores with a strong preference for algae and biofilm. They are the only common aquarium shrimp that reliably eats black brush algae (BBA) — the dark tufted algae that grows on driftwood and slow-growing plants. They will clear a BBA outbreak in a 20 gallon within two weeks if you have 4–5 of them. They also eat hair algae, thread algae, fuzz algae, green dust algae, and diatom films. They do not eat green spot algae (that is a Nerite snail job) or established blue-green algae (cyano — that requires blackout or chemical treatment).

In an algae-free tank, supplement with shrimp pellets (Sera Shrimp Natural, Bacter AE), blanched vegetables (spinach, zucchini, kale, cucumber), and the occasional frozen bloodworm or brine shrimp. Feed 2–3 times per week in addition to their grazing. Amanos are aggressive feeders and will steal food from fish and other shrimp — drop pellets at night when the fish are less active, or target-feed them with long tweezers. Remove uneaten vegetables after 24 hours to prevent water fouling.

Calcium matters for molting, just as it does for all shrimp. Maintain GH at 4–10 dGH or supplement with cuttlebone, crushed coral, or mineral stones. Amano molts are dramatic — you will sometimes find a complete, perfect 'ghost' of the shrimp lying on the substrate, including legs and antennae. Leave molts in the tank; shrimp eat them to recover calcium. A failed molt (shrimp dies mid-molt, half in and half out of the old shell) is almost always a water hardness problem — raise GH gradually over a week.

Common Health Issues

Amano Shrimp are hardy when water parameters are stable. The main health issues are molting problems (soft water — fix with calcium and higher GH), bacterial infections (often introduced with new shrimp — quarantine new arrivals for two weeks before adding to a colony), and pesticide poisoning (never use insecticides, bug sprays, or air fresheners in the same room as a shrimp tank — aerosols drift into the water and kill shrimp at trace levels).

They are extremely sensitive to copper. Many fish medications contain copper; many plant fertilisers contain copper as a micronutrient; tap water in some areas has trace copper. Always use a dechlorinator that neutralises heavy metals (Seachem Prime, API Stress Coat+) for water changes, and never dose a copper medication in a tank containing any shrimp. If you must treat a fish in a shared tank with copper, remove the shrimp to a separate container for the duration of treatment plus a week of activated carbon filtration afterward.

Lifespan is typically 2–3 years — longer than Cherry Shrimp, which average 1–2 years. They reach adult size in 6–8 months and continue growing slowly for the rest of their lives. The single biggest cause of premature death in Amano colonies is jumping: they are excellent jumpers and will escape through any gap in the lid. A tight-fitting lid or rim of foam is non-negotiable. The second biggest cause is a sudden ammonia or nitrite spike from overfeeding — shrimp are far more sensitive to ammonia than fish.

Breeding

Amano Shrimp cannot breed in freshwater. This is the single most important thing to know about them. Females carry eggs and release larvae, but the larvae are planktonic and require brackish water (specific gravity 1.010–1.020) to develop through their larval stage. In a freshwater tank, every larva dies within a few days. If you see a female Amano with a saddle of greenish eggs under her abdomen, that is normal — she will release the larvae, and they will all die. This is not a failure on your part; it is the species' biology.

Breeding Amano Shrimp in captivity is genuinely difficult and is not a project for beginners. The process requires: (1) a female carrying eggs, (2) a separate brackish grow-out tank at 1.010–1.020 specific gravity, (3) moving the female to the brackish tank immediately before she releases larvae, (4) feeding the larvae marine invert foods (phytoplankton, rotifers, or commercially available 'shrimp larval food'), (5) gradually acclimating the surviving post-larval shrimp back to freshwater over a week. Survival rates are typically 5–15% even with experienced keepers. Most hobbyists simply buy new adult Amanos when their colony ages out.

Sexing: females are larger, have a straighter abdomen with a curved 'saddle' of developing eggs visible through the back, and develop white or greenish 'saddle' marks on the side of the carapace when carrying eggs. Males are smaller, slimmer, and have a more transparent body. A group of 5 Amanos will usually contain at least one of each sex; if you want guaranteed breeding stock (even though breeding is impractical), ask the seller for 3 females and 2 males. For algae control purposes, sex does not matter — both sexes graze equally aggressively.

Frequently Asked Questions