Amano Shrimp Care Guide: Size, Tank Mates & Algae Control

If your planted tank already has a hair algae problem that Neocaridina shrimp couldn't touch, you're in the right place. Amano shrimp (Caridina japonica, also called Caridina multidentata) are the bigger, hungrier cousin of the cherry shrimp you may already keep. This guide covers sizing your tank correctly, feeding them once the algae runs out, and why they almost never breed in a home aquarium — so you know exactly what you're signing up for.

Quick Answer: Amano shrimp (Caridina japonica) grow to 1.5–2 inches, live 2–3 years, and are one of the most effective algae-eating shrimp for freshwater tanks. Keep them in groups of 1 shrimp per 5–10 gallons in water between 65–80°F and pH 6.5–7.5, and expect them to need supplemental feeding once algae supply drops.

What Is Caridina Japonica (Amano Shrimp)?

Caridina japonica is a freshwater algae-eating shrimp native to Japan, Korea, and Taiwan, popularized in the aquarium hobby by botanist Takashi Amano. It's larger and more translucent-gray than Neocaridina species, with a broken line of dashes running down each side of its body.

Taxonomically, it's classified under the genus Caridina in the family Atyidae [1], the same filter-feeding shrimp family as cherry and Neocaridina shrimp. If you've already read our Neocaridina shrimp care guide, the general husbandry will feel familiar — but Amano shrimp are noticeably bigger eaters and bigger bodies.

• Scientific name: Caridina japonica (syn. Caridina multidentata)
• Common names: Amano shrimp, algae shrimp
• Origin: Japan, Korea, Taiwan (mountain streams)
• Hobby popularity: Introduced to the US aquarium trade in the 1990s

Pro Tip: If you're used to sexing cherry shrimp by color, don't try that with Amanos — both sexes are translucent gray-green. Instead, look at the dash pattern: females have longer, more continuous dashes along the belly line.

Amano Shrimp Size and Lifespan

Amano shrimp reach 1.5 to 2 inches long, roughly double the size of a full-grown cherry shrimp. That size difference is the whole reason keepers upgrade to Amanos when Neocaridina shrimp aren't clearing algae fast enough.

They also live longer than most dwarf shrimp species, typically 2 to 3 years in stable conditions. Some keeper-reported tanks have documented individuals reaching 5 years with excellent water quality.

Recommendation: if your main goal is breeding a self-sustaining shrimp colony, stick with cherry shrimp. If your goal is clearing algae, Amano shrimp win.

Tank Setup and Water Parameters

Amano shrimp need stable, well-cycled water with temperatures between 65°F and 80°F and a pH of 6.5 to 7.5. They're hardier than many dwarf shrimp when it comes to temperature swings, but they're just as sensitive to ammonia and copper.

A fully cycled tank is non-negotiable. Never add Amano shrimp to a tank that's less than 4-6 weeks old, since they're highly sensitive to ammonia spikes during cycling.

Key parameters to hit:

• Temperature: 65–80°F (mid-70s is ideal for most community tanks)
• pH: 6.5–7.5
• GH (general hardness): 4–8 dGH
• KH (carbonate hardness): 2–6 dKH
• Ammonia/nitrite: 0 ppm, always
• Tank size: minimum 10 gallons; 1 shrimp per 5–10 gallons is a safe stocking rate

Common Myth: "Amano shrimp need a species-only tank to survive." Reality: Amano shrimp do fine in community tanks with peaceful fish. The real risk is fast, large predatory fish — not tank mates in general.

If you're moving Amano shrimp from a bag or a different tank, drip acclimation matters even more than it does with Neocaridina, since sudden parameter shifts are the most common cause of early shrimp deaths. Our beginner's guide to shrimp acclimation walks through the full drip method step by step.

How Many Amano Shrimp Do You Need for Algae Control

Most keepers stock 1 Amano shrimp per 5 to 10 gallons for effective algae control in a lightly to moderately algae-affected tank. For a serious hair algae outbreak, err toward the higher end of that density.

Amano shrimp earned their reputation because they'll eat algae types many fish and snails ignore, including thread algae and some soft green hair algae. The Seriously Fish algae shrimp glossary entry [2] describes this group of shrimp as some of the most reliable soft-algae grazers in the freshwater hobby.

Stocking guide by tank size:

1. 10-gallon tank: 2–3 Amano shrimp
2. 20-gallon tank: 4–6 Amano shrimp
3. 40-gallon tank: 8–12 Amano shrimp
4. 55-gallon+ tank: scale at roughly 1 per 5–8 gallons

Once algae supply runs low, Amanos will still need food — they don't stop eating just because the algae is gone. That's the part most first-time buyers miss.

Feeding Amano Shrimp Beyond Algae

Amano shrimp are omnivorous scavengers, not pure algae-eating machines, so they need supplemental food once algae growth slows. Skipping this step is one of the most common reasons keepers report thinning, lethargic shrimp a few months in.

Offer blanched vegetables like zucchini or spinach 2–3 times per week, plus a dedicated shrimp-safe sinking food. Our best shrimp food guide breaks down specific brands and feeding schedules by tank type.

A shrimp-specific wafer, such as the Hikari shrimp cuisine on Amazon, gives balanced nutrition without overloading the tank with excess protein. Calcium is especially important for molting shrimp — a cuttlebone or shrimp mineral supplement helps prevent soft-shell and failed molts.

Pro Tip: If your tank still has hair algae, hold off on supplemental feeding for the first 2–3 weeks. Let the shrimp clear the algae first — feeding too early just trains them to ignore it.

New to shrimp keeping in general? Check out our Neocaridina shrimp care guide for the water-quality and cycling basics that apply to every dwarf shrimp species, Amanos included.

Why Amano Shrimp Rarely Breed in Home Aquariums

Amano shrimp almost never breed successfully in a standard freshwater aquarium because their larvae need brackish or full saltwater to survive. This is the single biggest surprise for keepers coming from easy-breeding Neocaridina shrimp.

Females do carry eggs in freshwater, and eggs will hatch into free-swimming larvae. But those larvae are planktonic and require brackish conditions to develop past the first few days [3].

Research on atyid shrimp life cycles supports this pattern across the Caridina genus more broadly, showing that many stream-dwelling species evolved a larval stage tied to estuarine or coastal water [4]. In practice, that means:

• Freshwater-only tanks will see eggs and hatching, but larvae die within days
• Dedicated breeders raise larvae in a separate brackish-water rearing tank
• Juveniles are moved back to freshwater once they morph into recognizable shrimp form
• This is why almost all Amano shrimp sold in stores are wild-caught or farm-raised in coastal facilities, not tank-bred

Common Myth: "If my Amano shrimp is carrying eggs, I'll end up with a shrimp colony like my cherry shrimp." Reality: without a brackish larval-rearing setup, those larvae will not survive past the first week or two.

If a self-sustaining breeding colony is your goal, that's a strong argument for sticking with cherry shrimp instead, which breed readily in plain freshwater.

Common Mistakes When Keeping Amano Shrimp

The most common Amano shrimp mistake is adding them to an uncycled tank or a tank with unstable parameters. Because they're sold as a "beginner" algae solution, many first-time buyers skip the same cycling and acclimation steps they'd take more seriously with fish.

Other frequent mistakes:

• Buying too few for the algae problem: 1–2 shrimp in a 20-gallon tank with heavy algae won't make a visible dent
• Assuming they'll breed freely: leads to disappointment when larvae disappear within days
• Skipping copper checks: many fertilizers and medications contain copper, which is lethal to shrimp in small doses
• Not feeding once algae clears: results in slow starvation over several weeks
• Housing with large or aggressive fish: bigger cichlids and some barbs will pick off Amano shrimp over time

Pro Tip: Before adding any new plant fertilizer or medication to a tank with Amano shrimp, check the label for copper sulfate. It's one of the fastest ways to wipe out an entire shrimp population.

Tank Mates and Compatibility

Amano shrimp do best with small, peaceful fish that won't view a 1.5–2 inch shrimp as a snack. Their larger size compared to Neocaridina shrimp actually makes them safer to keep with slightly bigger community fish.

Good tank mate options:

1. Small tetras (neon, ember, rasboras)
2. Corydoras catfish — peaceful bottom dwellers, minimal competition
3. Otocinclus catfish — another algae-eating species that coexists well
4. Nerite snails — no competition for food niches

Avoid pairing Amano shrimp with:

• Larger cichlids or oscars
• Bettas known for fin-nipping or shrimp-hunting tendencies
• Crayfish, which will actively prey on shrimp

As of August 2026, community-tank stocking advice across most 2026 fishkeeping forums still points to the same core rule: match shrimp size to fish mouth size, and you'll avoid most predation losses.