Amano shrimp care guide: size, diet, tank mates and algae control

01

Amano shrimp at a glance

The amano shrimp became famous through Takashi Amano, the Japanese aquascaper who popularized it in the 1980s and 1990s as a natural way to keep algae out of planted layouts. Decades later, it is still the go-to algae-eating shrimp for planted tanks and community aquariums.

Amanos are larger, bolder and longer-lived than cherry shrimp, and their size makes them safe with many small and medium community fish. The trade-off is that they almost never reproduce in a home aquarium, so every amano you own was either wild-caught or raised in a specialist hatchery.

• Tank: 10 gallons or more, planted and mature
• Group: 3–5 for a 10-gallon tank, about 1 per 2–3 gallons in larger tanks
• Lid: essential, amanos climb tubing and escape
• Filter: covered intake or sponge filter
• Food: algae, plus wafers or pellets when algae runs out

02

Origin and natural habitat

Caridina multidentata, long sold as Caridina japonica, lives in short, fast coastal rivers in Japan and Taiwan. Adults live in freshwater among rocks and plants, but the species is amphidromous: females release larvae that drift downstream to the sea, develop in salt water, then migrate back upriver as juveniles.

This life cycle explains two things about amanos in aquariums. They are strong, adaptable shrimp used to changing conditions, and they cannot complete their development in a freshwater tank.

03

Amano shrimp size and lifespan

Amano shrimp size is one of their main advantages. Adults usually reach 1.2–2 inches (3–5 cm), with females at the top of that range. Females show a continuous line of dashes along the side and a broader underside for carrying eggs; males are smaller with evenly spaced dots.

Expect 2–3 years of life in a stable tank, and many keepers report amanos living considerably longer. Their bodies are mostly translucent grey with a brown or bluish tint, and they take on some color from what they eat.

04

Tank size and setup

A 10-gallon (38 L) aquarium is a practical minimum for a small group. Amanos are active foragers that roam the whole tank, and a larger volume also produces more algae and biofilm for them to eat. A 20-gallon tank with 5–8 amanos is a classic planted setup; see our picks for the best 20-gallon aquarium.

Add them to a fully cycled, mature tank only: amanos are hardy once settled but sensitive to ammonia, nitrite and copper. Give them plants, wood and rock to climb and graze. A tight lid is non-negotiable, since amanos will climb heater cords and filter tubes, particularly in the first days or when water quality drops.

Any filter works if the intake is covered with a sponge. A sponge filter doubles as a grazing surface, and amanos are often seen picking it clean.

05

Water parameters

Amanos tolerate a wider range than most shrimp, which is one reason they suit community tanks. Treat tap water with a water conditioner that removes chloramine, keep the temperature steady and avoid large, sudden water changes that can trigger stressful molts. Our guide to aquarium water parameters explains how to read GH and KH results.

06

Amano shrimp diet and algae eating

The amano shrimp diet is the reason most people buy them. They eat hair algae, thread algae, soft green film algae, biofilm, leftover fish food and decaying plant matter, working through moss and stem plants with their tiny claw fans. A group can clear soft filamentous algae from a planted tank within weeks.

Be realistic about what they can do. Amanos make little impression on hard green spot algae, and they are not a reliable cure for black beard algae, although some will nibble at it. They also cannot fix the cause of an algae problem, which is usually too much light or too many nutrients.

Once algae runs low, feed them: algae wafers, shrimp pellets, blanched zucchini or spinach a few times a week. In a community tank they will also grab sinking food meant for corydoras or plecos. An underfed amano may start nibbling soft plant leaves, so watch your plants as a hunger signal.

07

Behavior and tank mates

Amano shrimp are peaceful toward fish and other invertebrates, though they can be pushy at feeding time and will snatch food from slower tank mates, including cherry shrimp. They are active during the day and much more visible than smaller shrimp.

Their size protects them from many small fish. Tetras, rasboras, otocinclus, corydoras, dwarf gouramis and most bettas generally leave adult amanos alone. Large or predatory fish, such as big cichlids, adult angelfish, goldfish and most loaches, will eat them. See our guide to shrimp tank mates for a full compatibility list.

• Good companions: small tetras, rasboras, otocinclus, corydoras, nerite snails, cherry shrimp
• Case by case: bettas, dwarf gouramis, juvenile angelfish
• Avoid: large cichlids, goldfish, clown loaches, pufferfish

08

Breeding amano shrimp

Female amanos regularly carry eggs in aquariums, which surprises many owners. The eggs hatch into tiny larvae after about 4–6 weeks. In nature, these larvae drift to the sea. In a freshwater tank they die within a few days, so no amano population ever builds up on its own.

Captive breeding is possible but demanding: the larvae must be moved into brackish water that is gradually raised to full marine salinity, fed microalgae for several weeks until they metamorphose, then slowly acclimated back to freshwater. This is a project for experienced breeders, not something to plan for in a community tank.

09

Health problems and molting

Healthy amanos molt every few weeks and leave a clear, intact shell behind. Leave it in the tank so they can recycle the minerals. Repeated failed molts or a shrimp stuck in its old shell usually mean GH is too low or water parameters have swung suddenly.

New amanos are often stressed by transport. Drip-acclimate them over 1–2 hours using the method in our guide on how to acclimate fish. Losses in the first days are common with weakened stock. If several shrimp die later, test ammonia and nitrite at once and read our page on ammonia poisoning, which covers the same water problems.

10

Recommended gear

Amanos need the same basics as other shrimp: a covered filter intake or a sponge filter, a dechlorinator, a tight lid and a liquid test kit that includes GH and KH. A stable aquarium heater helps if your room temperature varies a lot.

If algae is the problem you want them to solve, look at the light as well. A controllable LED from our best aquarium light guide, set to 6–8 hours a day, prevents algae more effectively than any clean-up crew.